I don't want to spend $$$ on an ablative
multi-season coating if it's not necessary, nor do I want to paint the
thing any more than is absolutely necessary. Suggestions?

If a can of better paint is "expensive" maybe you shouldn't have bought the
boat. A can of ablative paint may cost a little more than some other type but
it won't build up since it washes away and you will save money in the long run
because you won't be paying someone to remove 5 layers of paint someday.
S/V Express 30 "Ringmaster"
Trains are a winter sport