Im not sure how the Ether kit works, or if the setup is regulated, I would imagine it is. You can get propane bottles exactly like the ether bottles. I screwed a propane bottle on the mount for looks but I really havent tried to activate the ether switch when driving. I understand the regulator scenerio,If the jetting would work with the ether start setup, It seems all I would have to do is get a hose that went from that threading to a normal 5gal Propane bottle and hit the switch when I need that extra boost.
Now your idea is nice, placing a regulator on the bottle and using a valve, if the line was done correct enough, dont you think the engine heat would be enough to warm the line prior to the injection to the motor? Can you provide any pictures of the setup you are using? How well does it work for you?