Thoughts: 6.5' bed v. 8' bed

For me, I like a four door truck. Add an 8 foot box to that and you are taking up a lot of real-estate. I commonly hear the argument of the long beds are better for towing due to the longer wheel base. But a short bed with a 4 door cab is the same length as a long bed with a two door cab. So virtually no difference in towing. Also the short bed fits in my garage.
As for hauling plywood or drywall, if it's only a few sheets I leave the tailgate up. If it is going to be a heavy load, put the tailgate down and use ratchet straps to tie it in. Actually, I tie it in either way.