We had LivinLite put in a cassette toilet in our C11FDB instead of the standard toilet + sub-floor waste tank. We found that if you are sitting on the toilet your feet dangle above the floor because of the shower floor well. I don't know if the standard toilets have the same ergonomic issue. To address it we built a drop-in wood platform built of cedar 2x4's. It just sits there over top of the shower drain & doesn't interfere with drainage. As you can see in the pic - we built it with a dropped center section so the maximum ceiling height is not reduced very much. The two higher side platforms give your feet support surfaces. The cedar was finished with tung oil. The pic shows the wood a bit dirty from dirt from our shoes. It would be easy to 'freshen up' the look with a bit of sandpaper & a new oil treatment.
(http://s28.postimg.org/5efw9s025/DSCF3216.jpg)By the way the bowl of the cassette toilet swivels so there can be a bit more room if you were taking a shower. (I haven't taken one in the camper yet). If anyone has questions about cassette toilets please feel free to ask.