On most of the filon there is only a millimeter or so of wood remaining attached. I would like to try a chemical stripper before resorting to sanding. I might go get a heat gun after work tonight and give that a go. Any thoughts on how filon reacts to heat? Should I worry about warping it?
I wouldn't use heat gun, there is a possibility of getting some bubbles with that. Acetone softens a lot of adhesives but you definitely won't like using that. Same for MEK.
If it was me, I'd try to remove anything loose, mechanically. Maybe spread an epoxy type of resin over any really rough surfaces. Your replacement sheeting would then have a good surface to bond to.