I am not of the opinion the HOA can regulate issues not agreed upon in the covenants (contract) or added via an amendment that meets the requirements of the covenants.

My former HOA used to send me letters saying I couldn't park my truck with trailer on the street in front of my house. It was usually overnight when I had returned from hunting and was too tired to put it up behind a fence. At first, responded that it was a public street, the covenants didn't address it, and they had no jurisdiction. They periodically would send them again. Finally, I resorted to writing "Go Fuck Yourself" in large red print on the notice, signing it and mailing it back to them. After doing that a half dozen times they quit sending me the notices.