After having the 8-foot bed for 7 years on our old truck I definitely wanted an 8 foot on the new truck so there was no decision for me. Being a full-time RVer I wanted the extra room in the bed for storage. I'm able to have two large tool chests forward of the hitch and also have room for more things behind it.
I've read too that a longer wheelbase truck is a little more stable when towing.
The downside is turning radius sucks and parking a 21-foot truck, but like I said I was used to that from the previous truck and we do the full-time thing so pros outweighed the cons for me.
For payload and towing weights truck companies put out charts each year. It gets you the ballpark and then things can change slightly depending on the truck's options. example - https://www.ramtruck.ca/documents/ramtruck/specifications/2018-ramtruck-3500-specifications-en.pdf
You can see from the chart bed size has a minor effect, so does crew cab versus mega cab.
My payload dropped from 4320lbs to 3995lbs on the door sticker because I added the factory hitch and an Aisin heavy-duty transmission that is heavier than the stock Chrysler tranny.
I'm with Ray, on our old set-up we had a 8 foot box on our truck and pulled our 40' 5er for 8 years. As fulltimers and "Off-Grid RVers" I loved the extra space for storage in the bed.
Here is our old 5th wheel and truck..............
We have a different "animal" than most now.........
Happy Trails!!!
Well, we soon will have a 8' x 10' bed on our "Little Pick-up" truck.....
As soon as I get it finished.
This pandemic stay-at-home thing got my creative juices flowing.........
Have a short bed Dodge Cummins 2500 now pulling a 35’ Jayco with square front corners (uh oh). Original RV had round corners. Had to install a adjustable sliding 5th wheel to prevent interference when turning.
Yes, would like the extra space for carrying “stuff” in the truck bed. Truck came as part of package deal with RV. Now have 223,000 miles on “Baby Huey” and still running strong with no oil consumption.
@LYNNE There is also the issue with the hitch in a short-bed truck to consider. Most have a 'slider' that moves in a turn.
When I went from a Class C Motorhome to a 35' fifth wheel, we already had a 8' 4 door 1-ton dually.
We bought it to haul out boat and horse trailer and didn't want to be lacking in towing capacity.
Like @Ray has mentioned, it's a pain to park sometimes but it's a work horse fit for the job.
I would prefer to have more capacity than not-enough, wouldn't you agree?
Oh yes, I would agree, last truck we had was a 1 ton single axle short box, but we had a TT then. We currently have a Class B and thinking of selling next year.