I'm hoping you have a bypass setup for the water heater. There's no sense in wasting a lot of antifreeze filling it up. I used the pink stuff for years but now just use my air compressor to thoroughly blow out the water from the water lines.
Don't forget to put a cup of antifreeze down the traps in the shower and both sinks so the traps don't freeze and break.
It's not required but being anal, I use a syphon hose stuck through the water heater drain to pull another 1/2 gallon of water out of the bottom of the water heater every time I store the RV (even if it's just for a week).