This does not answer your question, Melissa, but it addresses the comment earlier in this thread (I just read the thread.), that of mobility. I honestly don't know what kind of porta-potty we have. Hubby bought it at Sears. It works fine, although I find the pump flusher to be a pain and just fill a cup from the faucet.
I have an arthritic knee. We replaced the toilets in our house with ADA-approved toilets. These are 17" high. (I don't know why this is not the standard height!)
The porta-potty in our Uhaul
was a problem. We first raised it by putting it on an un-opened hose package. It worked but if you were prone to sea-sickness, it could give you that. It was not steady. So we found one of those wooden shower floors at Camping World. We did not open the package, simply put it un-opened under the porta-potty.
That worked for a year. This year, we stacked another on top. This must be a bit higher than our 17" ADA toilets, but it works great. If I don't have the height, my knee cracks and then is painful.