I'm a new user. A youngster with a 1994 F150 Flareside Ext. cab. Semi-luxury mods from Mark III on my girl. In the future, I plan the replace the rear seat with a futon bed (that need not fully extend).

Please take this seriously and consider and share the realistic challenges you believe I would face doing so. If anyone is willing to go with such a ludicrus idea, I would appreciate any advice you would have in completing this.

 

The first challenge is going to be mounting to the floor. There is no way something intended for household use is going to match up to the existing holes. This means you are going to have to drill holes and use brackets to attach the futon to the floor. Obviously you would want one with a metal frame rather than legs per se.
Second issue would be seatbelts. You'll need to create openings in the mattress that the belts can pass through.
Are you missing the jump seat that comes with the truck?

 

Some solid fabrication skills are definitely in order to make it suitable for automotive use. Remember, a seat is a safety device. Also, I think one would run into dimensional issues as well. My 97 Expedition's cargo/rear seat area is roughly 4ft wide by 7ft long. Making a bi-fold futon fit in place of the rear seat would be tricky and involve modifying the mattress by cutting it down and re-sewing it. I don't know about y'all, but I'm not that good with sewing. Except for reattaching some buttons, the last time I did sew was 20 years ago. Measuring is your friend here.

Perhaps it would be simpler to transplant a rear seat from a more plushy vehicle like a Navigator or Mark VIII?