35U Living Room Slide Out Floor Construction?

[BobC]

Can anyone tell me how the floor of my 2002 Itasca Suncruiser (same as Adventurer) 35U's couch/dinette slide-out is constructed?

I'm in the process of anchoring two recliners to the slide-out floor and the top layer is obviously thin since screws pull out easily. I was wondering if the bottom layer is thicker plywood I could screw into and, if so, how thick it might be. If it's not substantial enough, I'll need to through-bolt the anchoring brackets, but, if so, I'll need something that doesn't protrude too much and interfere with the sliding process.

I suppose I could drill a test hole but I thought I'd ask here first.