Gas smell in seat- and rust question...
 

Hello- I have posted about the wonderful fuel smell- and how I ended up getting a new aluminum tank made. So far MUCH better- but, the gas smell is still inside the car. I pulled the rear seat and here are my two issues;
First- fuel from leaking tank seeped thru and soaked into the 'fiber-board' backing of the back seat. Can clearly smell it- So HOW do I clean that?
If I try to wash it, worried the fiber-board will soften with water;
I thought of sanding it out- not sure how deep its soaked in;
Sealing with rubberized paint of some sort?
I have not been able to find a replacement seat back to buy... The upholstery needs some repairs, so happy to pull it off the backing and get it repaired...
Thoughts on best way to proceed?

Second- after pulling the seat- it appears the rear window had a leak- the small back 'deck' board is warped- I can get new press-board and redo it. But water ran down behind the seat and settled in the bottom- and rusted out. Photos below. I have sanded and put neutralizer on the metal. I see what looks like fiberglass insulation under there.
Should I sand, prime, paint and put new sound deadening in- and put it back together? I could weld a piece in- its all curved and won't be pretty- but it is under the seat, so who cares. It seems there is a second layer of metal under the fiberglass. Thoughts on that? thank you in advance...
https://cimg5.ibsrv.net/gimg/www.jag...da8a0f35fb.jpg
https://cimg8.ibsrv.net/gimg/www.jag...8e0f28f503.jpg

There is a void under the seat shaped metal, I am pretty sure and it may be that there is noise insulation in the void.
Either way the hole needs cleaning back to bare metal, and the void checked for rust and then welding, and if there is a void, spray some anti-rust in there.
If no void and it is the over-asle insulation, then this is an axle out and insulation shield out job, I am afraid. When/if done, treat the metal on the inside with Rust Bullet or similar. Also look at the floor pans which might be going home too.

The seat smell will never go, either rebuild the seat with new board or buy a seat from a parts car to replace yours.

Thanks- I can cut and do the metal- since it doesn't have to be really nice- As for the seat- I will keep looking- thanks!!