Is V(L/D)max equivalent to best glide speed regardless of weight, engine, height, etc.? I've read Carson's paper on V(L/D)max, and while theoretically interesting, it does not seem to me to be useful in actually finding the V(L/D)max of an arbitrary aircraft, as it assumes knowledge of total parasite area (f) which can only really be calculated experimentally (and is very hard to calculate at that).  

Another paper, by Russ Erb, claims that optimal glide speed, in the emergency section of the Pilot's Handbook for an aircraft, is equal to V(L/D)max for that aircraft.  This sounds wrong intuitively as it does not seem to take into account weight, air pressure, height, or other such variables.  As a math major, I am certainly suspicious of people who say "I'll spare you the derivations."

For an aircraft with an engine, such as a Cessna or a Bonanza, is best glide speed roughly equal to V(L/D)max?

I was told by an experienced pilot that 


  Vldmax at weight G = Vldmax at weight L * ( weight G / weight L )^0.5


This would seem to contradict the claim that V(L/D)max = best glide speed, as best glide speed (according to the Bonanza Operating Handbook, as an example), is constant.
According to the FAA's "Best Glide Speed and Distance" handout provided by the General Aviation Joint Steering Committee ("GAJSC"), on most airplanes, the best glide speed is halfway between Vx and Vy. See Exhibit 1