Years ago I knew a lady who worked in a dry cleaning shop.
She told me to do like they did, put a layer of metal down first,
(foil) then mattress padding, then an old, well washed WOOL blanket, cut to fit, add some heat proof fabric on top if needed. This has worked for me for many years.The greenish
wool has faded, but still irons well. I have a fold up into the wall
ironing board, so I don't have to look at this ugly thing all the time. But it still does the job.