Funny thing about RV waste tanks.....they are just holding tanks.
Uness you plan on leaving the 'stuff' in the holding tank for extended periods Rid-X will not ave enough time to eat the stuff.
Chemicals are also not really needed as they just make the stuff smell like perfumed poop.
Except for an occasional sniff when flushing (just like a regular toilet) you should have NO odors from your holding tanks inside the RV.
Waste tanks have vent lines, have seals on lines to/from tank and other means of 'vapor barriers' to keep odors out of rig (toilet bowl holding water---vapor barrier; 'P' traps holding water---vapor barrier; toilet floor flange---mechanical barrier; Air Admittance Valves---mechanical barrier).
Use chemicals, enzymes, odor controls etc if you want..they aren't going to hurt anything but they are not necessary.
Use of water is all that is really needed.