I can't answer your question directly (re. I don't know of a publication or app that tells you about age-restricted campgrounds, limits on self-containment, etc.).
I can tell you we van camped for years, and then did several years camping a small, vintage 1961
Scotty. Of course neither of those setups had gray water containment, nor did my 1964
Bambi II Airstream when I first got it. I never had a problem with age-restriction or with gray water containment questions.
Hit State Parks, small mom-and-pop campgrounds, and KOAs. There is little judgment there. Be smart and discreet about how you camp. Use of a blue boy or some other means to carry gray water off usually raises no eyebrows. Watering the surrounding trees every once in a while does not either. I watched a pop-up camper tow his blue boy to the dump station 2-3 times per day when camping at the Williamsburg, VA KOA. No one batted an eyelash...and it is a very nice campground.
Avoid the hoity-toity campgrounds. You'll know them when you see them or see their ads. Just avoid them. You don't want to camp with anyone who would not appreciate your vintage beauty.
I have added a gray tank to my Bambi and am in the process of doing so with my '61 TradeWind project. It is a nice feature to have...even for quick overnights in a Wal Mart parking lot.