Here is the foam I got and when I sit on it does not compress much at all. I have not cut it yet. I have enough for 2 maybe 3 seats. The less amount of area of the foam that will be when it is on the seat I know will mean it will compress more, but I am going to widen the rear half of the seat some for sure.
I have seen the older Schwinn mfr made rear shocks on the rear bar supports. Only all I could find was someone selling it like it was an antique and asking gobs of money.
I realized it is not too tricky an idea to do like I saw in your pictures. That seat is a marvel.
I am going to look to see where the pieces I cut off the rear bars support for the banana seat as they were too long initially.
Then I can sand off the chrome and see how my MIG can weld to it.
Maybe welding is not necessary there, but making the seat from scratch could for me be first better modify by widening (weld metal) the back section of the banana seat.
In another thread about raising the PCV valve (oil breather) I am getting automotive size breather and also going to have it remotely placed up higher with an oil separator I make myself. Since it is in the area of the seat post and close to the twin jack shafts, I will first see that space for it is designated before starting welding on the seat.
This is my plan, but my work area is pretty much been eliminated til a cooler time of year. I would work outside and apartment life has designated a no anything zone. Well not quite, but better that I get a good paying job and move where I have space to work.
Getting the ideas in mind and some light work dissembling the seat and getting a starting point I can do this weekend though.
Forgot, the seat from when it was on the bike before start of build had a bit seat post up a few inches. Now it is as low down as can be so I can straddle the engine and covers and touch the ground. No shock on the front can be easy to do, but just maybe a pivot so it can use a rear shock on the seat.
The exhaust and muffler is under the seat and do no present burn problem as it is now to the seat, tire, or me. I'll have to take that into account if I add rear seat shocks.
Foam I ordered
Other thread fixing PCV valve issue