Screw this adapter into the water supply port of your LQ. Attach an air compressor with the pressure set at a max of ~ 35 psi. Open your drain valves and faucets one at a time, until the water is replaced with air. Once you have clear air present, the line is air purged and ready for storage.

http://www.amazon.com/Camco-36143-Brass-Quick-Connect/dp/B002XL2IEA

Some WalMarts also sell a plastic version for half the brass cost. You can save a few bucks, but give up the long term durability.

The air purging will work on all your water supply lines. You will still have to use a small amount of antifreeze in the drain traps, shower, sink(s) etc. The hot water heater should be bypassed and drained separately.

The air purging is much faster and less expensive than purging with antifreeze. It is a commonly used maintenance in aircraft and marine applications and used by some RV dealers/owners. It works especially well for those who continuously use their LQs during the winter months, weekend to weekend.

Some brands of pumps can be run dry for a time, Shurflo and Flojet are two.

35 psi is less than a typical RV water system's operating pressure. Most electric pumps run in the 40 - 50 PSI range, and the optional RV water pressure regulators that monitor and adjust city water supplies for RVs, are also set in the 40 -50 PSI range. 35 PSI is a safe pressure to use for purging, that won't damage the water systems.