Our POPUP came with the CASSETTE POTTIE which has worked out great for us. They make two version one with a sit down shower/cassette pottie combo or a stand alone CASSETTE POTTIE. I recommend the stand alone version. In the five years we have had this setup i think we have used the sit down down shower only once. For us we either go to the camp ground shower or just do a stand up wash-up at the sink.
Since we very seldom use the shower part of this combo I would only install the stand alone version which will give you more floorspace..
This is what our shower/cassette pottie combo looks like and the stand alone cassette pottie.
The operation of these units is very easy and simple. They contain a 6-gallon water supply for flushing and everything stores in a pull-out tote tank which you can roll on its wheels to the bath house and pour down the toilet.
We have absolutely NO SMELL with this and it sits and feel just like the home toilet.
When not is use you can fold down a wood lid cover and use for storage of things...
I think your wife will really like these units. These units are self contained so no plumbing required.
We love ours in the OFF-ROAD POPUP.