Did you drain the water heater?
How about your outside shower - did those lines get blown out?
Did you drain the lines before blowing them out - otherwise there could be a low spot with water still in the lines. I prefer to drain the lines, and then fill the lines with antifreeze (although others have had success with just blowing them out- but you have to make sure the lines are empty of water).
Do you plan to leave your battery installed? Is it disconnected from any load? If it is fully charged and not subject to any loads from your trailer (like a propane detector, for example) it is probably all right to leave it installed. Otherwise, remove it and store it someplace protected from freezing and charge it up.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch