We are in the fortunate position of laying out the design of our new retirement home. Our rig is a 2003 Silverado 2500HD towing a 37ft 5th wheel. What I need to know is:
"What width of driveway to put in, and what radius curvature so that I can drive off the road and do a complete loop so that the rig is ready to drive forwards onto the road."

First off railbuff I'm jealous! 5 1/2 years and counting to retirement, already have the toys, just need the time! ):h

I'm not sure I totally understand your question, or if anyone is going to be able to answer your question without seeing the layout. I tow a 40' 5ver and I can pull it into my driveway (maybe 12' wide) with no additional turning space other than what is in the street, about 20 feet wide. However, every time I do this I leave a lot of rubber on the driveway, especially since it is a triple axle unit. :(

Sounds like a great idea to have an area to maneuver in. If it is tight you might be better off with gravel and avoid tire wear and strain on the suspension. JJ :)

I would look into the curb to curb turning radius of your truck.

That would give you your turning circle if your don't want to back-up during the turn.

Go to a big empty parking lot and give it a try. Then measure your distances.

Trailer suspensions were designed to take full GVW of trailer while turning sharp. You'll get a little tire scuff, but they'll survive.