"Marine/RV" TP is just cheap flimsy TP that dissolves quickly repackaged with a much higher price tag. Any "institutional grade" or no-name TP will work just fine in limited amounts in any marine toilet. A lot of boat owners by Scott sold at Sams and Costco by the case.If you're used to using big wads, you'll have to learn to cut back to 5-6 sheets 'cuz too much will clog the plumbing. If your toilet is one of the high end all china macerating electric "thrones," it can chew up any toilet paper, but again in limited amounts. NO WET WIPES IN ANY MARINE TOILET!!! No paper towels or tampons either. Those have to go in a waste basket...be sure to impress on your guests that even one will clog the toilet.. The rule of thumb is, nothing goes into the bowl that hasn't passed through you except quick-dissolve TP.
Eric was on the right track with his advice to dissolve a few sheets in water, but it's actually a lot easier than that: tear off a sheet or two and put it in a mason jar, large glass or a bowl of water. If, in an hour or two you stir the water or shake the jar and all you see is "snow" in milky water, it'll work just fine in any marine toilet. But if it's still an intact or mostly intact sheet, try another brand.
Shameless self-promotion alert: Although my book is titled "Get Rid of Boat Odors" (my publisher thought that title would attract more buyers than "Flush With Success") it's actually a comprehensive "marine toilets, holding tanks and everything related to marine sanitation 101" manual that answers at least 95% of the questions you're bound to have and more you haven't thought of yet. And I'm always glad to answer any it doesn't. The title in my signature is a link to it on Amazon...available in both hard copy and kindle. (end shameless self promotion).
Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein