This is one of the reasons I went to 19. 5's, and with the full alloy Alcoa's for all 6 wheels. The weight is more, but the aluminum wheels offset it, alot. Even with the adapters. But when I'm towing, it is perfect.
Rick, with your slide-in, you have to consider it. It will make the ride much better. And if the GS/A's are $187 a piece, the 225/70R19. 5's are right in the same ballpark on price, and plentiful. Now I went to 265/70-19. 5's and they are little over 2 inches taller than stock. And I believe they were around $225 a piece. This is a "G" rated tire, too. In a dual setup, rated for 5070 lbs. - each.
The ride is a little more stiff, but proper air pressure is crucial, loaded and unloaded. I pulled my original Goodyears off at 12K milles, and they have plenty of tread left.
Another reason I put the Rancho 9000's on. They help, too.
EB, I still have them, and if you get in a bind for new ones, let me know. Once you put the 19. 5's on, it's hard to go back to the 17's.