As to the screws, that looks fine for now IMO, but you might want to get some rubber washers to put under the screw heads?
I know nothing about the clear coat on the AS, so will not suggest anything to remove the rubber. Best to find the exact right solution, which is above my pay grade!
PS -- Edit -- I happen to like exposed fasteners like the screws, in a funny "form follows function" way. You are never going to hide completely the fact that a Fiamma plate was there, so why try to mask that? If you can remove the Fiamma strut from its base plate, you could re-mount the base plate, and find some new use for it!
Also, if you keep the parts your Airstream will be worth a little more when you sell it to buy a larger one . . .