Revisiting this, as plans have changed, again.
Now, we have removed the false floor from the bathroom, as I'm 6'3" and have to slouch to stand in the bathroom, and the tank will be mounted to a 7" riser system I am building to raise the camper so it fits on my gooseneck trailer better as a redneck toy hauler type design when we need it, and it'll still work on my flatbed truck with the riser.
Mounting the toilet directly to the camper floor, with a nice big 18ish gallon tank below it attached to the riser.
Thanks all for the help, but now I have a slew of new questions to post in a new thread :D