At the local autoparts store, I bought a package of tubeless tire stems. I then use the hole in the rubber end (opposite the valve), to push over the valve cap to remove it. If the cap's too tight, then stick some needle nose pliers in there first. This "tool" makes it very easy to put the cap back on. I always figured there is a commercial version of this "tool" but just don't see them at auto-part stores.
I then bought a package of four chrome metal valve extentions, and screwed two together, which makes an excellent long and straight extention. This will then screw right on to the valve. All problems solved for less than 10 bucks including parts for an extra set.
Hole size in wheel pant is 7/8".
L.Adamson