I see no-one has answered you yet so I will tell you what I did on my Boler
in case it helps.
I did a dinette conversion on mine so I had a similar situation to solve except mine was at the front.
I beefed up the "shelf" by sistering up a piece 1/4" ply. I varnished that to match my table but it was also to strengthen the existing wood there.
That wood was glassed in on mine so I didn't want to mess with removing it.
If you are talking about the rubbery insulation in the Boler
, it is more than likely the original Ensolite. Popular opinion tends to favor keeping it if it is at all salvageable. Easy to paint
over. Your paint
could be acrylic.
Hope this helps.