I believe your dual wheels are steel rims, which would preclude the use of solid extensions. Solid extensions can be used when there is a corresponding hole 180 degrees from the valve, as you would find on aluminum (Alcoa) rims.
In your case, with steel rims, the best and most economical solution would be good quality flexible extensions, with stainless steel outer protective sheath. These are sold at Camping World and other RV supply stores. If a choice is available, go for the better quality.
Proper installation is important, to prevent any vibration of the extenders which could loosen the valve itself. Of a rigid valve can be installed on the rim to replace the original rubber valve, the risk of vibration causing a leak can be minimized.
Remote pressure sensors are a more expensive alternative, but correctly installed flexible extenders are used by many RVers with success.