Q:

Tikz - Perspective Letter, rotated writing

I'm just working on a tikzpicture which represents a letter on which you look in a perspective. I just managed to realize this with the shadow and the perspective under Usage of xslant and rotation and shadows. 
The goal is to use this letter as a template for many letters. So I just thought about placing writing either with nodes in tikz (possiblity 1) or with textblocks (possibility 2) as you can see in the code. If that works I want to define a command, for example \address which includes everything from the code of the adress so that I only have to change the Names and streets an so on. 
All that is quite fine, but now I've got a problem:
The rotated writing in tikz is not really good, because it didn't rotate the line of the font but just the letters. And that's not really pretty :) Maybe there's another way to do this? I hope you can help me a little. Mayber you've got another idea for the problem? Thank you.
(The possiblity 2 in this way is not very useful, because it won't rotate the block, just the letters...)
Here's a working example:
\documentclass[a4paper]{scrartcl}

\usepackage[ngerman]{babel}
\usepackage{amsmath}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{tabu}
\usepackage{eurosym}
\usepackage{icomma}
\usepackage[absolute,overlay]{textpos}
\usepackage{pgf, tikz, pgfplots}
\usepackage{rotating}
\usepackage{graphicx}

\usetikzlibrary{
            arrows,
            shapes,
            shadows.blur,
            positioning,
            calc,
            intersections,
            decorations.text,
            backgrounds,
            plotmarks,
            shadings
}

\begin{document}
\begin{tikzpicture}[rotate=-3,xslant=0.1,scale=0.7,every node/.style={xslant=0.1,transform shape,rotate=1}]
\fill [color=black!20!white,opacity=0.5] (0.15,-2.15) -- (13.15,-2.15) -- (15.15,-20.15) -- (0.15,-20.15) -- cycle;
\draw [color=black!30, fill=white] (0,-2) -- (13,-2) -- (15,-20) -- (7.3,-20) arc (270:220:9.9cm and 3.5cm) arc (-20:0:4cm and 15cm) -- cycle;
%possibility 1:
\node at (1.5,-5.2) [right] {\scriptsize{XXX YYY}};
\node at (1.5,-5.6) [right] {\scriptsize{ZZZ Street}};
\node at (1.5,-6) [right] {\scriptsize{012345 AAAAA}};
\end{tikzpicture}
%possibility 2:
\begin{textblock*}{10cm}(7cm,7cm)
\begin{rotate}{-3}
\parbox[t]{10cm}{Lorem Ipsum\\ Blab\\Bla\\bla\\D\\D\\D\\D\\D}
\end{rotate}
\end{textblock*}
\end{document}

A:

This is loosely based on my answer at Plot 3D stacked squares with shadow, which employs Bruno's method at Shear transform a "box"
\documentclass{article}
\usepackage{xcolor,graphicx}
\usepackage[usestackEOL]{stackengine}
\newsavebox{\foobox}
\newcommand{\slantbox}[2][.5]{\mbox{%
        \sbox{\foobox}{#2}%
        \hskip\wd\foobox
        \pdfsave
        \pdfsetmatrix{1 0 #1 1}%
        \llap{\usebox{\foobox}}%
        \pdfrestore
}}
\def\mycell#1#2{\fcolorbox{black!50}{#1}{#2 }}
\def\makeply#1#2{\mycell{#2}{\Longstack[l]{#1}}}
\def\perspective#1#2{%
\rotatebox{\myrotate}{\slantbox[\myslant]{%
  \makeply{#1}{#2}}}
}
\begin{document}
\def\myrotate{-5} \def\myslant{.3} 
\perspective{XXX YYY\\ZZZ Street\\012345 AAAAA}{gray!30}

This is back to normal text.
\end{document}

Changing the values, \def\myrotate{-10} \def\myslant{.7}, for example, changes the perspective:

Here is the method adapted into the user's MWE:

and here it is with the coloring removed
\documentclass[a4paper]{scrartcl}

\usepackage[ngerman]{babel}
\usepackage{amsmath}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{tabu}
\usepackage{eurosym}
\usepackage{icomma}
\usepackage[absolute,overlay]{textpos}
\usepackage{pgf, tikz, pgfplots}
\usepackage{rotating}
\usepackage{graphicx}

\usetikzlibrary{
            arrows,
            shapes,
            shadows.blur,
            positioning,
            calc,
            intersections,
            decorations.text,
            backgrounds,
            plotmarks,
            shadings
}
\usepackage{xcolor,graphicx}
\usepackage[usestackEOL]{stackengine}
\newsavebox{\foobox}
\newcommand{\slantbox}[2][.5]{\mbox{%
        \sbox{\foobox}{#2}%
        \hskip\wd\foobox
        \pdfsave
        \pdfsetmatrix{1 0 #1 1}%
        \llap{\usebox{\foobox}}%
        \pdfrestore
}}
\def\mycell#1#2#3{\fcolorbox{#3}{#1}{#2 }}
\newcommand\makeply[3]{\mycell{#2}{\Longunderstack[l]{#1}}{#3}}
\newcommand\perspective[3][black!30]{%
\rotatebox{\myrotate}{\slantbox[\myslant]{%
  \makeply{#2}{#3}{#1}}}
}
\begin{document}
\def\myrotate{1} \def\myslant{.1} 

\begin{tikzpicture}[rotate=-3,xslant=0.1,scale=0.7,every node/.style={xslant=0.1,transform shape,rotate=1}]
\fill [color=black!20!white,opacity=0.5] (0.15,-2.15) -- (13.15,-2.15) -- (15.15,-20.15) -- (0.15,-20.15) -- cycle;
\draw [color=black!30, fill=white] (0,-2) -- (13,-2) -- (15,-20) -- (7.3,-20) arc (270:220:9.9cm and 3.5cm) arc (-20:0:4cm and 15cm) -- cycle;
%possibility 1:
\node at (1.5,-5.2) [right] {\scriptsize{XXX YYY}};
\node at (1.5,-5.6) [right] {\scriptsize{ZZZ Street}};
\node at (1.5,-6) [right] {\scriptsize{012345 AAAAA}};
\end{tikzpicture}
%possibility 2:
\begin{textblock*}{10cm}(7cm,7cm)
\begin{rotate}{-3}
\perspective[white]{Lorem Ipsum\\ Blab\\Bla\\bla\\D\\D\\D\\D\\D}{white}
\end{rotate}
\end{textblock*}
\end{document}

A parbox input could be implemented by defining
\newcommand\makeply[3]{\mycell{#2}{\parbox[t]{2in}{#1}}{#3}}

However, in either case {\Longstack or \parbox), this answer is not "true" perspective with a vanishing point, but rather an isometric rendition.  Thus, while the text may be slanted, it will not get wider towards the bottom of the page.

A:

Obviously only a partial answer, but you can align node labels sloped to a baseline.
Maybe you can somehow use the text as a node label for a line that is sloped correctly as your text.
\documentclass{standalone}

\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
    \fill (0,0) circle (0.1);
    \fill (3,-1) circle (0.1);
    \draw (0,0) -- (3,-1) node [midway, above, sloped] {Sloped text};
\end{tikzpicture}
\end{document}

In your (nice looking) example you could use something like this below. Obviously with white instead of red as line color and better fitting coordinates.
\draw [red] (1.6,-5.2) -- (4.05,-4) node [black, midway, sloped] {\scriptsize{XXX YYY}} ;
\draw [red] (1.6,-5.6) -- (4,-5.5) node [black, midway, sloped] {\scriptsize{ZZZ Street}};
\draw [red] (1.6,-6)  -- (3.95,-7.05) node [black, midway, sloped] {\scriptsize{012345 AAAAA}};

