> They had a few go rounds with the HOA, but they can't regulate antennas.
That's a little bit of an overstatement. HOAs can regulate antennas unless the FCC (or Congress) makes an exception.
In the case of WISP, there is an exception that applies: 47 CFR 1.4000 [1]. WISPs would fall under the exception for antennas for "fixed wireless signals". A "fixed wireless signal" is "any commercial non-broadcast communications signals transmitted via wireless technology to and/or from a fixed customer location".
You don't have to convince them, let the FCC do that. I lived in an area with a heavy handed HOA. The only decent broadband was a WISP. They had a few go rounds with the HOA, but they can't regulate antennas. In the end the WISP put a tower on my roof - I never heard a word. They may try, but they don't have authority to regulate it.