Dave wrote:

:-) Thanks ;-)
Being resourceful (SWMBO says "tight") I was thinking more of a widget to
adapt a tyre pressure gauge ('seems like it should work) or some other
ingenious way of adapting something I might already have.

Yes, easy enoough to do. But you'll get the inside of your tyre gauge
wet. Depending on the type of gauge, this may not do it much good.

--
Grunff