Our half bath is on the passenger side, as is most units with half baths. The sewer pipe crosses over the frame and will cause a clog, especially if you have lots of girls using the toilet or lots of #2's. We try to use the rear full bath when stationery and the half while traveling or just run more water through it. You can level the coach a bit Listing to Port an it will help a bit. With mine...it's one of those sacrifices for convenience. If this is happening on the driver side toilets where they are mounted just over, or very close to the black tank, I would have to investigate how much paper they use and/or run a bit more water through on each flush. You can also do the "double flush", whereby you flush just after #2's departure, then another flush when the "paper work" is done.
2018 THOR Chateau 35SF
Two Labs, Bugsie & Blondie