I would not question the TT you want to get. Some dont need alot of space for their family and others want as much as possible. IMO, I want as much possible.. The more space the kids have, the less the clean up to do in these small campers. I cant wait to upgrade next year to our next step up the larger TT ladder.
My only thought is that the 150 weighs less than the 250, that extra weigth for the 3/4 ton trucks keeps you a lot more stable on the road and safer. A short bed 250 is not that much different to drive than a 150 for a daily driver. You will FEEL more comfortable towing with any 3/4 truck with the weights you are looking at. My buddy pulls just about the same weights and length you are talking about with his ECO 150, and he says he gets blown around alot.