Well, you need a pressure gauge shaped like this to measure the pressures on Inner and outer wheels.
It works well unless your outer wheels have unusually short valve stems. I bought tires at Costco and asked for their longest stems, which aren’t particularly long and have no trouble.
So, it stands to reason that you also need a fairly long inflater tool with the straight tip for the inner wheel and slanted backward one for the outer. This is no trouble to buy for a compressor made with a hose designed to screw onto tools. All large compressors are but you have to be careful buying portable inflators which often have just the tip made to screw onto the valve stem of a bicycle wheel. I have needed air several times while on a trip and while I carry an inflator tool I made a point of stopping at a tire shop which will already have the right tool. I always got told “no charge” because these guys don’t want anyone to have tires causing an accident. I always offer a $5 bill or a coffee and doughnut if a store carrying them is nearby.