I don't know about what you saw, but Harley does not use base gaskets, just an o-ring around the spigot that rests right on the edge of the bore into the case.

I just went out my very cold garage to look at the cylinder base area of my '08 SERK.
Getting down to a parallel plane under the TB area, I see no possible signs of anything between the cylinder base and the crankcase. Even in the areas that the cylinder hangs back just a bit from the case machined surface edge, there are no exposed gasket edges to see.
Without seeing the parts breakdown of the cylinder head/gasket and reading past threads on the subject, it makes sense to just use an o-ring for sealing this area because as they say, there shouldn't be anything in the stud holes but studs.
Bottom line is sounding very redundant at this point, fix the head gaskets/cylinder sleeve creeping and the base leak goes away.