I used plastic version of the brass "Sharkbite" PEX fittings for an upgrade to my TC as noted
in this thread. They are a lot easier to work with compared the "Flair-It" fittings. The hardest part of manipulating the Flair fittings was not as much getting the connectors apart, but rather reinstalling them... while reaching in and under the cabinets!
There is one significant image in that thread that, due to how long ago I posted the original thread, that Tiny Pic no longer hosts it... the explanation of what I did is imaged below. It basically added additional valves to isolate the city water attachment to the camper and and the outdoor shower that had no way of being winter-isolated for winter use while using internal plumbing in winter conditions. The shark-bit in the image is on either side of the newly installed valve towards the lower right if the picture.
Granted, TC's are much different from other rigs and do not know if your plumbing components are the same. I am not sure what "Tuffpex" is but if your rig has Flair-it fittings then perhaps it is feasible. Not sure if this helps or answers your question but good luck in your endeavors: