Got tired of trying to add and check air on the inner dually tire.
So I took a 13 inch valve extender.Added a washer to hold it as I filled it up. And it's flexible so you can screw it on and off.
As far as taking the valve cap off.I used a couple of extensions with a 3/8 socket to take it off and put back on.
Didn't have a 3/8 hose so that might have been easier.*
And I don't have to leave the valve extender in all the time*
Which would not work with my rims.