As a retired OTR driver I'll tell you to go ahead and use the truck island air, but be prepared to wait in line sometimes and check them out first. Why--because many of them don't work, have broken nozzles or air hoses, or are turned off. As for the coin operated machines--it will cost you plenty of quarters to air your MH tires as they are timed with relatively small compressors that take awhile to fill larger tires.
You didn't mention what type of MH you have, if it is a gas unit do as macantic
said, get a good compressor. If you have a DP get an air hose and tap into your own air supply and depending where your air governor is set, you should be able to air your tires to 105-120 PSI.
Hope this helps you.
Tom and Barb
2000 Bounder 39Z