I have use a 3rd row mini van seat before like from mid 1990s fits great also used universal seat brackets from summit so it will slide stock brackets too tall and have it recovered of course
I used a seat out of a chrysler mini van, I don't remember which one but I did cut the front and taper it like the body, fits great.
Chrystler Voyager middle seat werks well but you will have to make mounting brackets.I have one in my 28 rpu.
i narrowed a 90s s-10 seat and had a seat cover made . it fits like it was made for it plus its on stock ajustable slides so you can move back and forth
School bus seats work real well. Google search used shool bus parts for your part of the country, the will be a bus wrecking yard somewhere near you.
I've used the mini van seats in the past but in my 32 pickup I used plywood and high density foam,,works great. HRP
I used the double wide, not the bucket seat out of a pontoon boat. Had a fifty's look to it in my 31-A.
Mine is in a '31 pu. Mini van (Caravan) seat middle row from late 90's/2000 m.y. Fab attachment to suit.
Mid 80's Mazda van center seat. Left off the folding arm rest on the p***enger side. S****ped the original mounts, 4 bolts and it was off. Modified a late 70's set of sliders off a mid sized Ford. Seat slides back and forth about 6", back angle is adjustable and allows access to behinde the seat. Original fabric will make a good pattern for re-upholstery. Going to modify the original Model A seat sides to hide the sliders and hinge. Fits like it was designed for the body. Canuck
summit sells new jeep rear seats, that are real nice low backs, I wonder if they will be wide enough?