We also have a 05' Aerolite Cub.....
#1 First your going to open up your fresh water tank valve and the drain that. That is all you have to do here.
#2 Next, open up your "low point drains". Those will be under the trailer somewhere, near the outer edge. We have one set on either side of the trailer. One under the area of the kitchen cabinets, and the other under the bathroom. Now each set will have a hot and a cold drain cap....Open both and let the water drain....But be careful how you "unscrew" the drain cap. I hold the line with one hand, and use a wrench to loosen the cap. Our caps are plastic and colored coded (red & blue). The reason you want to hold the line with one hand, is if you don't, you have a chance of twisting the line and causing the next threaded connection inside the trailer to get loose.
#3 For the hot water tank, you will want to drain it. Should be a threaded plastic cap to open up and drain it. You can lift the handle on the check valve to make the water come out faster. Then go inside and switch the valves for the by-pass for the hot water tank. You have the cold water line going into the hot water tank. Close that valve...and close the valve coming out of the tank. Now "open" the valve between those two valves. So there are 3 valves you must turn. So now when you go to the next step which is blowing out any extra water in the lines, the air will by-pass the hot water tank.
#4 Next I will take my air hose (I have a small 3 gallon portable air compressor) and blow into the "city water" inlet. ""Not where you fill your fresh water tank"". You want the threaded "city water" inlet, which on our Cub is on the opposite sides of the trailer. I have a threaded barbed fitting I screw on. I will have my wife open up each water faucet inside the trailer one at a time and let the air blow out any extra water. Do the toilet also and if you have an outside shower, as we do. After take, I will disconnect the shower hose that runs from the tub faucet and let the water in the the hose drip out. I'll leave this off till spring. Make sure you do both hot and cold. My wife will hold a pan under each faucet to catch any water coming out, except the toilet. So with the low point drains open and doing each faucet, you know you have 99% of the water out of the lines.
#5 I will also put in RV antifreeze. So now I'll close up my "low point drains". In the cabinet where your water pump is I will disconnect the supply line coming from the fresh water tank. Get yourself a gallon jug of RV antifreeze (pink colored) from WalMart ($4). I bought a fitting and a 18" piece of hose that I now screw into the pump where I unscrewed it from the fresh water tank. Now I stick that in to the gallon jug of antifreeze and turn the pump on. Just by turning the pump on that should suck up 1/2 or 3/4 of the RV antifreeze. Then I will open up each faucet till a stream of pink water comes out, including the toilet and shower or tub faucet.
#6 I will also pour a dab of RV antifreeze into each drain (kitchen sink, bathroom sink & shower tub drain) just for added peace of mind. Usually one gallon of RV antifreeze is all you need.