Which is best for pulling a fifth wheel, short or long box?

I'm partial to long boxes, although I've owned two short box trucks as well. As far as towing a fifth wheel I myself would opt for a long box.

And as long as you're not committed to a trailer yet I'd also look into duallies right away. Never know where your trailer buying "adventure" is going to take you and with the dually you wouldn't have any towing concerns.

Dan