When I bought my SB F250, I was towing a bumper pull TH and also had short driveway issues which limited me to a standard cab LB or extended cab SB. After having both types of cabs, I would not go back to a standard cab. If it wasn't for the short driveway, I would have chosen the LB extended cab to get the larger fuel tank (greater range). In hindsight, I had less TC choices with my SB, but I also had a couple hundred pounds less weight with the smaller bed which went to payload.
Speaking of payload: Unless you plan to tow more than 5000 lbs behind your truck, get the gasoline engine. The reduced weight will go to your payload.
Overall, I am under 22' with the the TC and 45' with the enclosed trailer in tow. I am over GVWR but under axle capacities - I have upgraded the wheels and suspension so it handles the weight well. With my setup these upgrades would have been required with a F250 or F350 SRW, so choosing the lower GVWR model still saved me some money.
When you are looking for your truck, definitely choose the heavier suspension and anti-sway bars offered with the camper package. If you know you will upgrade the wheels to 19.5", get the least expensive steel wheels and sell them off to recover some costs.
