I had the same concern and recently installed a fan to extract air from the “shopvac/cyclone/bucket” compartment of my enclosure, it turned out to also be a solution to enable auto-start of my Festool vac. See this thread for details and a picture of the fan ($25 air extractor normally installed in kitchen/bathroom)
I cut a hole the diameter of the fan near the top of the left side of the compartment, and cut another hole the same size on the right side near the ground, for air intake. I thought cutting a large hole (~4") there would defeat the soundproofing, but honestly I cannot really tell the difference.
What I have not done is quantify the benefit in terms of how hot the shopvac compartement gets during long cuts, but now at least I know there is constant airflow there, it can only help. What I like most is that with the Festool plugged on my BitRunner, and this air extractor plugged on the Festool plug, both the dust collection and the air extraction fan turn on and off automatically at the beginning/end of a job. Very convenient.