I won't dispute your experience, but the type of hitch used shouldn't affect front end loading. But placement of the hitch certainly can. However, that 29RS has a dry pin weight of 1538 lbs and assuming your truck is a 145 inch wheelbase model, then locating the king pin 3 inches behind the rear axle will only reduce front end load by about 32 lbs. That little change should not affect steering feel.
Too bad you already changed trailers, a cheaper solution would have been to install a Ranch Hand bumper to put more weight back on the front axle. Actually, the problem was likely not the amount of weight on the front axle, but just the leverage that is applied to the truck by having the king pin behind the rear axle. If you had reversed the Andersen adapter moving the king pin in front of the rear axle, then that should have been all that was needed to improve steering feel.
