@twowheels19 Unfortunately, I don't think a 16.3" high toilet will fit. And the 17" length may also be an issue.
Went out and measured. The below image I took of a demo flagship back in summer 2023 (we did not get a portable toilet when we bought ours), but in a previous conversation, I used it to draw some dimension lines.
Height: 16" to 16 1/8" depending on where you measure.
L1: 23 1/4"
L2: 18" (not exact because the bend on the 45 degree section is a radius and not an angle)
W1: 16 5/8"
W2: 12" (not exact because the bend on the 45 degree section is a radius and not an angle)
The stock portable toilets (like pictured) have to sit sideways, but they can be used sitting sideways. Most separating toilets, like our Trelino, can not be used sitting sideways because things "don't line up", but luckily, many brands fit facing front to back.
I've noticed a lot of these small separating toilet manufacturers incorrectly call their products "Composting toilets" rather than "Separating toilets". Even the very large volume "composting toilets" with agitators fill up and need to be emptied long before any composting can take place. When they are cleaned/dumped, the solid bin content can be added to a dedicated compost pile where composting will take place over the following year. But contents should never just be spread on top of ground and left (should go with out saying, but some may get the incorrect impression that it can be spread anywhere since it's "compost". Even those big "composting" toilet need to be bagged and thrown in trash when on the road and not spread randomly, no matter how remote.
These smaller versions have even less hope of any composting occurring. It seems to be more a marketing phrase. Even if one used the toilet for a couple days worth of solids, added media and left it sit for a few months, no composting would occur. The media's job is to dry out the exterior of the solid, which greatly reduces odor, but it effectively mummifies the solids so no break down will occur. Think of exposed animal dropping that dries out on the exterior vs what happens when stepped on and the dry exterior makes way for not-so-dry interior.
Separating toilets can be used multiple times, for solids, by using drying media to encapsulate and dry the solids. They work much better if the paper is not added to the solids bin and are instead thrown in a separate trach bag. We've noticed that driving down bumpy trails means solids do not stay buried in the media, so while it's reasonable to use the same back and layer media while at a single camp spot, it works best to remove bag before driving.
We use our separating toilet regularly for liquids, but still prioritize using bathrooms, outhouses or digging cat holes if allowed (and weather/bugs permit). The separating toilet is our last option for solids, but it's very nice to have available. We use media, but we bag it before driving and have a dedicated dry bag, for the bagged-up solids to go into, which seals in scents completely (which is not the case if the bags are thrown into a non-sealed trash sack like a trasheroo or similar hanging on the back of the rig.
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