Hey OP, i also live in an HOA and this last round of elections we actually installed some maga pedes into power. Prior to gaining a foothold on the board, we actually used saul alinskies rules for radicals against them. we started with a flier campaign to get awareness among the sheep, called a special session once we had a quorum, and proceeded to vote on what we wanted.

I know this is seperate from your issue but wanted to share. My suggestion to your problem would be to formally request permission to display your sign, it sounds like you have your husband already on the board so id imagine it would only require one or two more members. Another course of action would be to randomly put the sign up during peak visibility, once the hoa responds, take it down for a few days and then put it back up. HOA's have to go through formal process to actually impose a fine on you. at some point the hoa members and the complaining karens will give up, Saul Alinskie's rules for radicals baby, amp up the conflict