Model 2100 Winterization-antifreeze into system??

I just purchased a 2005 Phoenix Cruiser 2100, and it now resides in Northern Idaho, so I need to winterize it.  Is there a way to pump antifreeze into the lines without putting the antifreeze into the main water tank.  On my Trail lite trailer, there is a "T" and a valve on the intake line to the water pump, which allows you to turn off flow from the main water tank and pump right from a gallon of antifreeze.  Also, are flat screen tvs and DVD players subject to damage at very low temperatures?  Should they be removed?  On occassion we can get very cold, -15F, not often though.  Thanks for any suggestions.

I also recently purchased a Phoenix (2551), I am located in Massachusetts when it also gets cold. Phoenix recommended to me to add 2 gal of antifreeze to the water tank and pump thru the system. Flush out in spring. I didn't like that idea so I exposed the water pump system and saw that there is no bypass to add the antifreeze directly to the pump. So I ordered a Camco kit from Amazon for $15 to add the tee and a short hose to add antifreeze directly to the pump and just drain the main tank. Standard 1/2 fititngs from Home Depot could also be rigged up.  I also have a small air compressor to blow out the line using the city water fitting to get rid of most of the water and drain the water heater. Just using air by the way would also work without the antifreeze, but I prefer the added safety of antifreeze in the lines and the water pump. In addition I will dump some antifreeze in the Black tank and pump it thru the macerator pump. Close the valve and leave it. I can still use the black tank in the winter as long as the macerator pump stays full he f antifreeze. Just re-add antifreeze after pump out.