Our toilet is on the right side and dumps straight into the black tank. Our black tank pretty much extends across the width of the motorhome.
I have heard of some RV's (forgot whether they were motorhomes, trailers, fifth wheels or whatever) that have a pipe that runs some length to the black tank. I could see that might increase the chance of a problem. But I don't know if that's related at all to which side the toilet is located on. Probably has more to do with where they decide to locate the waste tanks.
~Rick
