I have no experience with coatings so can't speak to that side of things.
What I have found helps with bigger blobs of tar (which I typically find inside the barrels of wheels) when using a typical tar removal product is to gently use a plastic razor to cut off the bulk of it, then, I take a cotton disc (the fairer sex usually uses them for make detailing their faces), wet it with the tar remover and plonk it on the glob of tar.
This dramatically extends the dwell time as the tar removers, being liquid, generally tend to run off the blob quite quickly reducing any 'rubbing' that needs to occur.
I have accidentally clayed over a spot where some tar remover residue remained and it definitely isn't nice... the caly becomes greasy/smeary and sticks to the paint, so I wouldn't advise that. But yes, you could clay the tar off, using clay and lube (no tar remover) and it would work, but IME the shaved off tar bits that are then embedded in the clay do tend to show their presence on the paint thereafter, so I prefer to try and get the tar off chemically as opposed to claying.