You can use the air outlet in the battery bay. As per a YouTube video from a few years ago, I made a device that makes that easier than it otherwise would be. Without that the compressor cycles on and off. Before the compressor kicks on in a cycle, the tank pressure is well below that of the tire, so you can actually lose tire air, and may never get up to the target tire pressure.
You can remove the inflator when you think tank psi just reached existing tire psi, and go tap the brakes to get the compressor to cycle back up, then run out and reconnect the inflator hose, yadda, yadda... The problem is the tank maxes out around 120-130, not that much above most of our common needs tire wise.
By using the home-built device, you can keep cycling the compressor to its max without having to remove the inflator line and run back and forth to the brake pedal to drop tank psi to get the compressor on, over and over. The red valve releases sub-100psi compressor air from the tank, not the tire, getting it to cycle back on and max back up. My device fits in a small Rubbermaid tub with enough hose to reach any tire from the curbside rearmost “bay”.
I have other portable compressors and some here use quality ViAir ones. But when I used my device the first time it worked so well that I subsequently only use the portable(s) in the toad. Portables can heat up before a huge coach tire is full, due to their low volume, and their safety thermo breakers cut out the units until they cool... a long, slow, “on”, cutout, wait to cool, “on”, slog.
Reference this old thread:
http://beaveramb.org/forum/index.php/topic,4277.msg32439.html#msg32439Joel