Welcome to the forum Kent and Corrie! We have a section on Winterizing which describes each method, with antifreeze and only using compressed air-http://www.jaycoowners.com/showthread.php?t=4848
If you are sure you have ALL the water out of the system then there is no need for antifreeze except to pour some in the p-traps and a little in the black/grey water holding tanks. For some reason even when I blow out the lines to get the water out I still add the antifreeze to be sure, I suppose I doubt myself just a bit. It only takes about 1.5 to 2 gallons if the water heater tank is bypassed and drained, as described in the link.