If you want cooling i would mount a heatsink that connects outside/inside with waterproof mounting. That way you get the nice airflow from the outside without getting dirt or water inside the case.
Yes my prototype builds had little channels and exposed heatsinks. But i have stopped doing that because i dont think its needed. I have ridden many km on boards that have no fans or ducts and there is no issue with heat.
I printed these last night to see what they would look like. Still debating it they will actually help. Thought about putting one in the rear center backwards and it should cause a bit of a vacuum to help suck the air out.
Heat sinks that protrude out of the enclosure slightly, but are still sealed, would be perfect. Direct Mosfets with thermal paste to a heatsink and then it has fins that poke outside of the enclosure with heat resistant silicon around to seal it. That would be the best idea.
If you look at tablets and laptops they’re all going fan less now- copper barso pulling heat away and putting it in other location to passively radiate. Would be easier to just drill some holes tho lol