If you can't put a sign out in the yard perhaps you can at least put a sign in the window of your houses. That is how I get around it here in CA.
Good luck! Try giving:
FLAIR REAL ESTATE
(409) 769-5495 office
a call and ask him, he is very knowledgeable about Southeast Texas!
Statistics show that For Sale signs account for very few home sales, but they are helpful in assisting people to find your home once they are in your development. They also help your neighbors who may be looking to move into a new unit in your development - they may be renters, or they may be wanting to move up to a larger unit.
That said, the internet is your best advertising resource if used properly. Most Realtors only use a fraction of the internet's capabilities, so be sure to hire a Realtor who knows how to maximize your home's exposure online.
Another thing to consider is a flyer in a flyer box at the entrance to the community with all of the homes for sale in the HOA. You could advertise an open house on that as well.