Have you talked to the HOA board and asked if you can get a variance? If you have some plans that would show what it would look like (i.e., it'll look as good or better than anything else in the neighborhood), how you'll manage noise from inside and out (i.e., no late night grinding that keeps light sleeping neighbors up), etc.?
The risk is that you give away your secret. The reward is that they could say: "sure, sounds good."
I do know that they will break your balls if you sneak around them and they figure it out. It's a power thing and when people feel wronged they will do everything in their power to make your life miserable, including making you tear it down. Crazier stuff has happened with HOAs around here.