My '47 has more or less the same thing, but mine is vertical. My guess these are to prevent 'stuff' from getting under the seat... maybe to prevent anything from fouling the seat adjuster?
They are for a foot rest. My 1941 ford 2dr ( I no longer have ) has the foot rest still in place. Really a cool item!
mine has them. carpet covered. actually never saw any for sale. Check with Mark Kicsak 607 7291693. he has a TON of '41 stuff.
As I recall they weren't really padded just an upholstered foot rest so it would be easy to just make a set