Fleetwood Angler Roof and cap maintenance

[Osprey]

I just bought a used 2001 Fleetwood Angler truck camper. I have a Lance and a Newmar 5th wheel in Arizona. The Fleetwood is for us to use when we are in Alaska (our home base).

I need to caulk things like: where the ladder attaches to the roof and I need to replace at least 6 of the clearance lights.

I discovered the roof is really soft and the previous owner said you have to be sure to step on the support beams. Much different than my lance where I can actually store boats etc on top. The front cap is also very soft like it has little support and is sort of a soft fiberglass rather than a hard shell like the lance.

I would like to know how these lights and ladder supports can screw into this "fabric" and not into supporting structure? It seems to hold and there are no leaks. I just don't want to create a bunch of work or leaks.

I knew Fleetwood products are built cheap and this one is built lite. That is why I bought it. It allowed me to use my current truck without exceeding my payload capacity.

Questions:
What do the screws hold on to?

What type sealant do you use to mount the clearance lights and other components such as fridge vent, vent caps, ladder, etc....

Why is the nose cap so soft?