I "winterized" our Pleasure Way Pursuit yesterday. I drained the water tank down to about 8 gal. and poured 3 gal. of RV anti freeze into the tank. Then I ran all the sink faucets both hot and cold, ...
I agree that it has to be a relatively decent compressor, but a five gallon compressor, approximately $150 - $200 does the job nicely. Also, you must let it blow, tap by tap for about 5 minutes each, and this will clear the "droplets" out of any line. This isn't a big deal to do, just use common sense, and make sure that all of the openings have been blown out.