I see nobody has answered this question and didn't want you to feel left out. I know a lot of real estate agents don't jump up and down over rentals.
I am not familiar with the areas you are looking to rent in but have you tried looking on sites like Craigslist? Sometimes the MLS (Multiple Listing Service) does not have many rental listings. I know San Diego has a strong rental market and people usually leave real estate agents out of the picture because they can rent it out themselves using signs, websites etc.
Also, if your looking for an older 55+ community, do you have any friends or family in the area that may help you find such a spot. This website is a guide for 55+ communities. http://www.55communityguide.com
Perhaps this can help you out.
Sorry I was not able to help you more but I am not familiar with this area. Hope you are able to work something out! :)