For those that may not know, a Trekker was a 4Runner type conversion (maybe even a prototype to test the SUV market) Winnebago did for a Toyota in 81-83.

Been kind of throwing around some ideas for the back seat of my '81. The stock (or what I assume it stock) back seat frame has just about had it. It is made of some 3/4" box tubing and 3/4" or 1" angle.
I suck at MS paint but thought I would see what you guys thought
Stock is 38x15.25 for the seat up right, fold over is 38x14.25"

Option A would be to go:
38x18" for the seat back and 38x10" for the fold over. The two pieces are connected by a piano type hinge that allows the upper seat back to fold and form a floor when folded flat.
Advantage of going a few inches higher on the seat back would be better support for the kids, I do plan on adding head rests. Rear view vision is about gone with my spare tire set up.. :

Edit: the seat bottom is a separate piece that rests on the floor of the bed...


Option B: Split fold down rear seats, each seat would be 18.875" wide and 18" tall with fold over being 18.875" (7/8")x10"
Advantages: able to carry three people and some long camping gear etc.
Disavantage: more work, maybe not at strong....
Either way, have got enough material to get either option built. Just need to decide. My friend Todd that helped me with the front end work said he will weld it up, I just need to try have everything pre cut...I would try it but it has been 20 years since I took High school metal shop..

Let me know what you guys think ;D

Current back seat:

Folded down (old pic)

 

If I understand your sketches you would only have 10" to sit on. I guess not a big deal for a kid, but it would not be very comfy for an adult. I like the split seat idea, but as you said it would be weaker. is it going to sit right on the floor? Or is it raised?

 

Oh, I am an idiot, The bottom piece is a separate piece. It basically just rests on the floor and is about 36" long x16" wide. It has to be removed to get the seat to fold flat.
The upper seat back is two pieces, connected by a piano type hinge and folds to go the length of the bed, just up to behind the front seats. When folded it rests on a lip molded into the bed...with the split seat I would have to have some form of support off the floor...

 

Sorry, I have never seen a trekker in person. With the weakness of a piano hinge I would go with the one piece. Seems like it would be a lot stronger.

 

Does the 10" piece just lay over the back of the seat when It is up? If so I could see the split seat working.

 

What did you end up building? Or is there another thread about the whole build process? I'm going to be restoring my Trekker soon and am looking for ideas and help.