If you want your trailer to be mobile, you need the present design. If you would have the RV planted in one spot, like a regular house, then you should covert to a house type toilet. A house type toilet would be heavier; water would slosh around in the tank; fresh water tank would empty quickly; black water tank would fill too soon. Park model units do have house type toilet because they aren't pulled down the road except when moved to semi-permanent locations.
2010 Jay Flight 23FB
99 Silverado 3/4 ton 6 liter 3.73
08 Polaris quad