You can purchase longer brass valve stems from a truck tire shop. They cost between 8 to 12 bucks but are designed to hold over 120 PSI.
The new units, when installed, can be bent to allow easy access for air pressure check. The initial installation cost can be cut if you find an installer that will break-down the tire and install without removing and re-balancing the tire/wheel assembly.
If you like I can call a friend and get ball park figures for you, as cost comparisons.
If you rotate the inner tires then this won't work for you unless you install them on the outers and use a dual foot chuck. Mike