Not trying to convince you or anyone else to change your thinking on a small size pickup bed. I haul a lot of things 8 feet and longer with a 6 foot bed. I have a rack I can slid in and out and haul on the rack just about any length of material a full size pickup bed can haul. I just hauld 20 sheets of 10 long pieces of tin roofing with end gate down and had a couple 2 x 4's under the load. I have never had to use a full size to do what a 6 foot box can do.
Just my view on the 8 foot verses the 6 foot box.
Of course you've never had to use a full size to do what a 6ft box can do.
But there are things that a 8ft box can do that a 6ft box can't do.
I have hauled 2 x 10 x 10 footers INSIDE the wife's minivan with the rear gate closed.
Regularly haul 4 x 8 ft sheets of plywood again inside the van.
My Dad regularly hauled 12 ft sheets of drywall in the back of his pickups. No way you can do that in a 6ft box.
You can haul 33% more wood chips, manure, gravel, or any other loose items in the back of a 8ft box than a 6ft box.
Also a truck with an extended cab or double cab can't haul (weight wise) or pull as much as a truck with a std cab and 8ft box can.
All this to point out stuff that a 6ft box can't do but a 8ft box can do.
Why limit how much work you can do unless there are other things that are more important. If that's so that's fine. At that point maybe a analysis of why a truck with a 6ft box is needed. If its just to haul the occasional couple of 10ft pcs of tin roofing a minivan could maybe do the job so the downside of having a pickup can be avoided.
a 6ft box is a compromise between a working truck and a truck that spends it time doing minvan stuff.