We had similar issues when we first got our camper. No matter how much water, and how little waste, it would clog up. We finally took it back to the dealer (under warranty and after several Flush King cleanouts) and they took apart the system. It turns out that there was a slight obstruction in the bend (did not dump straight down). Just enough to catch the smallest piece of paper and block the whole thing up. Glad I didn’t have to do that repair. Toilet has worked flawlessly now for last several years. Using the awning hook to clear nasty toilet blockages got old in a hurry!
It could be a structural issue with the pipes?