Natas
That's pretty good approach but will end up being kind of expensive. You need a regulator and that alone is a significant cost.
That's what's nice about a syringe, no valves (except the one on the propane torch head or the one built into the lighter) and since the measurement is done at atmospheric pressure you don't need a regulator.
I agree though, you can't beat the bling factor of an on board fuel and meter.