Steam ain't gonna fix that! Lol!
The Seat Shop sells the foam for the buckets. That can be made to work with some modification.
If you're unsure or leery of modifying the foam yourself, once you have the seat torn down, take that new foam & the complete original one to an upholstery shop & they can do the mods for you. They have the proper tools & glues to make it right.
The outside edge of the driver seat in any vehicle always takes a beating. There are a few tricks & mods that can be done in order for that outer edge to stand up better over the long run.
The metal pan of the seat cushion's frame has a bent edge around the perimeter. That edge work is good for giving that relatively thin metal it's strength, but not so good for the foam every time that you get in ior out.
The foam on that outer edge compresses, causing that metal to cut the foam.
When I work on these, I'll glue a couple layers of a good tough material on that bent edge of the pan. Then, on the bottom side of the foam, I'll glue another layer of material across the whole bottom of the foam. It will have to be sliced & diced in such a way that it forms to the shape of the underside of the foam. It doesn't have to be pretty, but it should be relatively smooth as any lumps or bumps will transfer through to your butt.
The new foam will come with some fabric on it. It's nothing more than a serviceable material that meets the basic, bare minimum requirements. It's a 'scrim' fabric that is easy to work with, but so basic bare minimum I won't even keep it in stock.
This may seem like overkill, but if I was to do this project, once it's done, I don't ever want to see it again! There's no $$$ in having to things 2x!
In my shop, this would be a 20 minute > 1/2 hour job.