What airfoil simulation software is suitable for a cut trailing edge? I'm looking for a way to simulate airfoils used to reduce turbulence.
airfoiltools.com already does this a long way.

However I have width and length limits, and I'm interested in comparing full profiles with profiles that are virtually longer but cut where the trailing end meets the boundary.

Can CAESES or SimFlow do this without too steep learning curve? (I'm a complete newbie.)

(Specifics: Chord 30 cm, width 25-30%, Reynolds number 1,500,000, NCrit 9, 50-70m/s)
One tool you might want to consider is MIT's XFoil. I'm not sure I fully understand what you'd like to do, but this tool is used in many of MIT undergraduate aerodynamics classes.

If you think it might work for your purposes, here is a course by the program's creator from MIT's OpenCourseWare site. Lecture 3 is a tutorial on how to use XFoil. You might want to browse the OpenCourseWare site for more advanced uses of XFoil, too.

Good luck!