Water Heater Plumbing

[sambam]

I've got the plumbing winterized, but am curious what to do about the line that runs from the water heater bypass valve to the water heater. My previous campers had the valve right at the heater itself, but on this camper it is in the convenience center so there is a good 12 feet between it and the tank. I researched it on this site, but didn't come up with any definitive answers. My idea is to take the anode rod out of the tank (which is already drained), open the valve and pump antifreeze until some runs out of the drain in the tank. Also, I'm guessing the line that runs from the hw tank has a check valve to prevent backflow, so would that have gotten winterized while pumping antifreeze through the hot water lines? Thanks for any advice.