yep, I'm sure that's the problem.... the pipe doesn't go straight down into the black tank but rather has a bend in the pipe and the paper is hanging up. I suggest that you do multiple flushes....once for the solids, then again for the paper. If more than normal paper is required, do multiple flushes with the paper.
An old friend of mine who had motor homes before I did, cautioned me when I was looking to purchase a new mh....he said the first thing I needed to do is look down the toilet and see if it goes straight into the black tank. If it doesn't, walk away and find another mh. I have followed his advice...for the most part. Our current mh's half bath's toilet does indeed go straight into the black tank, but the rear toilet is a macerator toilet and I hope it never clogs up!!
Good luck in your future flushes...
Ron