The Gulfstream (with an aft galley) is almost impossible to load outside the CG envelope. Frankly, there is little need (Part 91) to prove you're loaded within the CG envelope, because there's a 99.9% probability that you are.
A Legacy, on the other hand, is a different story. If I have lots of folks and fuel in the aux tanks, I'm going to be checking to see where the CG is - Part 91 or 135. This particular airplane will bump the front limit rather easily.
The point is that even though you're not required to do a W&B form under Part 91, you ARE required to assure the airplane is operated within the design CG envelope. You may have a need someday to PROVE you were operating within the envelope. I'd at least have the forms handy. So this is something else for sonic340 to be thinking about with his Ultra operations.
I agree. Its like the Lears, basically impossible to load them out of CG. A pilot must know his plane and the needs for it, like you explained with the Legacy. We always have the forms with us.