The cottage on our garden lot has a separate small room with it's own outside door where our predecessors had a chemical camping toilet. But that is a hassle, since it has to be emptied into a dumping station, for example at a campground, or taken home and emptied into the toilet. And you have to put toxic chemicals in it if you want to use it more than once. Some of the gardens have flush toilets with illegal cesspools, but I definitely didn't want to go that route either. Outhouses are absolutely taboo in this water protection area. Who would want one anyway?
So I started searching the internet for ideas, and lo and behold, there's a whole community out there discussing composting toilets, aka dry toilets. There's even an entire online book on the subject, The Humanure Handbook by Joseph Jenkins, which I found so convincing and informative that I decided to go that route. Thank you, Joseph Jenkins, for your great book!

Under the seat there's a bucket, which you line with a biodegradable bag and fill with a few inches of tree bark mulch before using. After each use, enough tree bark is sprinkled on top to cover the waste. Experience has shown that after about 6-8 uses (urine only), it's ready to be emptied.
The receptacle can be lifted out and fitted with a lid to carry to the compost heap. After depositing the bag and all there, possibly in an indentation, you pile enough fresh composting material (cut grass, branches, leaves, etc.) on top to cover it up. After about a year it is completely composted, faster if using a thermo composter.

So I'm sold! Highly recommended for light occasional use with easy access to plenty of compostable material and compost heap.