I'm not sure what it is about the first day of spring that would produce a sale on Porta Pottis, but both Amazon and Walmart have decided to offer the Thetford Curve Porta Potti for about half the going rate:
Given that you can manage free shipping of this not-insubstantial package, $85 is a really sweet deal.
Not that I want to come across as a great expert on portable toilets (not a major resume builder), but I have had pretty much all the sizes and variations. From the dozen, the Thetford Curve currently in my Sprinter conversion is our favorite. The capacity is good and it's sturdy. There's an available locking plate to hold it to the floor. The seat is comfortable and it's easy to clean and dump. Probably the best thing is that the height is close to normal home toilet height, making it pretty natural to use.
It won't squeeze into the same spaces as one of the foot-high two-gallon alternatives, but if you have the room, this is a toilet that's much more workable for frequent multi-day use.
I think I'll stop before this gets any weirder, though let me know if you have questions. Give it some thought.