I took the generic benroy profile, and constrained it. That means any dimension can be changed, at will, and the drawing updates automatically.
Why would I do that? To make it easy for you guys to do a "what if" scenaro...
Just download the trial copy of Turbocad Professional... (you can play with it for 15 days).
Lets do an example together.
Here is the drawing as it first opens up:

You decide that the 8' length looks too short for that 80" long bed. You could shorten the bed up to 72", or you could lengthen the benroy. Let's see what 10' looks like...

That looks too long to me. How about you? Well we could make it taller? You could try 54" or even 60" tall. But I am just going to shorten it up a little bit... Lets try 9' long...

That's not too bad. I would probably still play with the size and position of the door and wheel...
Let's turn on the dimensions and see how they look...

Do you want to work on that file a bit? How about you Rooster, since you are in the planning stages for a generic benroy.
Here's the file...
http://www.mikenchell.com/generic_benro ... ained2.TCW
The trial of TurboCAD professional is here...
http://imsi.vcrm2.com/broadbaseema/www/ ... urvey1.jsp
Have fun, and let me know if you have any questions... and or if I should add more detail to this file.
Mike...
P.S. Andrew, are you using Professional?