In my experience you are only going to be able to get the Dometic 310 Part-Timer RV Toilet # DOM57FR to fit if you have at least 10" from the wall to the center of the toilet flange. With you only having a 9" rough in it is going to limit you to the Dometic 300 # DOM64FR.
There is one situation where I have seen a toilet fit and that involved turning the unit sideways but again you will have to ensure you have the rough in clearance to the side as well as either a 4 post toilet flange... view full answer...