Lets say you stay within you payload capacity with all passengers seated, which is 1550lbs. in OP's example. And lets say you find a 5'r that you have loaded to a GVWR 8,000lbs. If you truck is at max GVWR say 7,000 lbs. and the 5th wheell axles are loaded to 7,000lbs. You have 14,000lbs...