I don't think the extended valves are the way to to, seem to remember several members complaining of the extend lines being torn off. I just went to local speed shop and picked up a truckers air pressure gauge. It's about one foot long and will reach the inner valve stem with no problem, the hardest part, for me at least, is getting my hand in there to remove the cap. They also make an air chuck, shaped similarly, that will reach in the inner tire to add air. You could probably pick these up at any auto parts store.
Scott W.