The lower panel sounds like it would be the intake combustion air and exhaust for the furnace? One sucks in and the other blows hot air out?
I have found the easy way to remove rivets is grinding but one can also tap a nick in the rivet and then drill it out. The nick will help keep the bit from walking and going too far off the head.
To replace, I then go back with small bolts with cone shaped heads to fitt into th erecess better.
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Richard
Why no RV year, make and floorplan on MY signature as we suggest for others?
I currently DO NOT have one!