So, after a lot of thinking (and a lot of help from other RVers), I have build my contraption to be able to air the inside tires while on the road, without having to carry the compressor.
It is a simple 12V air compressor qith digital gauge (On sale for 15.99 at Kmart), and a straight air chuck from IAPA. I set the air compressor to the desired preassure, and hold the chuck against the valve. Works perfect, weightts almost nothing, and is cheap. Here are some pictures:
Hope it helps somebody with my same problem.