It sounds to me like you are more concerned about the time period between your two trips when the trailer will still be in storage, is that right? Find the low point drain for your plumbing system and drain the water out. leave your faucets in the "on" position and you won't have any issues. You won't get all of the water out, but you will get enough that even if the water freezes there is enough room in the pipes for it to expand. You will want to flush the toilet dry and then put a little of the pink stuff in the bowl and you may want to put some down your sink traps.
2016 Sunset Trail 33BD
Tow Vehicle 2016 Nissan Titan XD 4x4, Crew Cab, SV with Cummins V-8