what I did
I have seats from 2017 ford transit vans.... they come on seaters, two seaters, and three seaters.... I have three wide and two wide. They have headrests, are cloth, have built in baby seat latch points, built in three point belts, they can recline a little like the seats in coach class in airplanes. I have medium blue and they are also come in coarcoal grey. the three wide seats, both outer seat positions have baby seat latch points, the two seaters - only one side has baby seat latch points. Almost for got... they have armrests too.
These seats mount like this.... there are rails that you bolt to the floor. The seats latch into the rails. If you put rails in different places, you can move the seats around. The rails stay put, the seats are the part that moves and latches into a different rail.
go to ebay and type in "ford transit van seats" Look around and you will see what I am talking about. The cheapest brand new ones I have seen are in the Phoenix arizona area. I paid $250 for my three seater in the Kansas City area. They are brand new never used. so are the ones in Phoenix. people that do up camper vans, or limosine vans buy the vans and dump the seats.
I also have front seats from chevrolet pickup trucks.... 2004-2007 cloth, built in three point belts, the one on the passenger side has baby seat latch points, head rests, arm rests, and recline to a point. I paid about $50-$75 for each one. Used but were all in very very good condition. Some folks must not have much in the way passengers in the pickups very often.
another option that is good but pricey is 2nd row seats from toyota siennas... find the ones with leg rests and built in seat belts.
I am finding several in facebook market place in the eureka ca area... seems to be quite a few out there.. hunt for the best deal.
there is a guy in Los Altos giving seats away....facebook market place.
telephone me if you want to talk mountings... or where to find them
william 785 207 7600