Chemical Toilet Use

Steve, I have the smallest Thetford on my boat. I always use fresh water for flushing, the unit is quite frugal with flushing water use. Out of curiosity to your question I just checked the Thetford site and they specifically mention 'freshwater flushing', no mention of salt water.
To further investigate I checked up on marine toilets since they do use salt water flushing. Apparently the salt water builds up scale in the pump passages. This could possibly make it to malfunction over a long time use. They suggest a little white vinegar in the flush water to dissolve any scale.
None of this would concern you on a camping trip, especially if you flush the salt water out afterwards.
I have no idea how the toilet chemicals are reacting to salt water, perhaps the stuff that goes into the lower tank would not mind since its made for much nastier material.
The stuff for the flush tank, which gives the water a pinkish colour, might not like the salt water. No doubt you'll find out about that :-0

Klaus

Shouldn't be a problem if you flush out the flush tank after. As for chemicals reacting to salt water, you pee in it and pee is very similar in composition to salt water..........well, maybe salt water with some alcohol added.

Steve,
The chemical I use in my porta loo states that it will work in fresh or salt water.
I don't know how the seals ect. in the loo will react to salt water though.
Regards
Steve