And yet I have not heard of major problems from people using this system with tubeless tyres. A few have said that they had to top the tyre up with a pump, but I haven't heard anyone saying it failed totally.
Your adapter with a valve sounds like a great idea. The little plastic adapter you get with the Rema type of system does look very flimsy. I really haven't a clue on this, though. When I got the kit I practised reaming the hole and fitting the mushrooms on a scrap tyre, but I didn't try the inflator because I didn't want to waste the CO2 cartridges. Having priced them up online, I can see that you don't want to use them unnecessarily.
OK, mini-pump it is - and a Slime compressor on my Christmas list
