I got under the seats (IE, pulled them) and unde that carpet. there has been a lot of bondo work, some of it is chipping up. So I cut some patches, forgoed the DocCAD, and will wait till tomorrow to rivet and drill, as i dont have a drill at the momrnt that lasts for more than 5 min on a charge.
on the plus side, I found some nice fire resistant foam to use as a sealant, so that should help a bit. Safety(ish) first!