When our front ride height valve failed (but still had all its guts in place) we made a temporary fix that kept us able to drive for a couple of weeks ...
Remove front linkage to front ride height valve (center of front axle), then manually rotate valve to "fill" position, when bags are filled where we need to drive, rotate back to center off position, then tape around valve to keep it in that location. Repeat as necessary.
Ride height valve has three very close settings, empty, off, fill. Rotate slowly as each setting is very close to the other settings.