My 09 Chevy dually handles my 1140 very well. I did a few mods to my suspension but the truck is rock solid. I do use a 42" hitch extension when towing my trailer. The difference in weight between the 990 and 1150 is about 300 lbs. Both of them will be in the 5000 lb range loaded and wet. Definitely the 1150 will offer you more room and probably a dry bath if you prefer that over a 990 wet bath. Both are great TCs and the 990 is still Northwoods most popular model. My guess is that the difference in total length of either hitch extension will be about 12-15", depending which TC you go with. As far as length of overhang, you should not know any difference once you get used to either.