All DPs have an air fitting in the front in case the coach needs to be towed, the fitting is tied to air brake system which has big storage tanks. The wrecker hooks an air hose from the truck to power and release the air brakes. On our Tuscany the air fitting was in roughly the same place as yours, under the hood usually on passenger side, some have a ball valve with the quick connection attached to it. I carried a 50 ft air hose with a quick connect that allowed me to reach all the tires with no problems.
Funny story. My brother was going to buy me a compressor for Christmas, said thanks but no thanks, didn't need one. He asked if I already had one and what size? I told him I had a 360 hp compressor, first I got a dumb look, then he wanted to know where I got one that big, where I kept it, and why!!! Waited awhile before I told him!
Dave & Myra
One day your life will flash before your eyes,
make sure it's worth watching!