I would be tempted to cover the heads of the fasteners, unless they're stainless. A decade of weather can be unkind.
Do you mean to cover rivet heads? If the rivets used are the type with holes that go right through, then yes (as I think I mentioned), they would need to be filled/covered somehow.
If you are using bronze or galvanized fasteners (seems unlikely, on a camper), I still would not cover the heads, and if they're stainless, they actually use oxygen
in order to remain "stainless."
Besides rivets, I can't think of any fasteners that would leak through the heads. The important thing is to get good coverage underneath the flange and under the fastener heads/alongside the fastener threads.
Professionally bedded boat hardware (hatches, cleats, portholes) does not get sealant placed on top of the fasteners (i.e. covering the heads) and it sees a lot of water - rain, spray, and "green" water (i.e. seawater, can come aboard with quite a bit of force).
In my experience, beads/globs of caulk along the edges of hardware and over the tops of fasteners is typically put on by people (owners) when the hardware is past due for re-bedding, and there is a leak, and they are looking for a quick "fix." Sooner or later (usually sooner) it continues to leak and then the item is pulled for proper re-bedding (re-sealing). I think it's easier to just pull and re-seal immediately (or prophylactically), because the beads don't really work and are a mess to clean off.