I have to store mine outside. Is that going to be the death of mine

?
My advice would be:
1) dont store on grass, the dew creates condensation on the PUP floor above it which will rot it; park on pavement or crushed stones.
2)check and touch up caulking at least twice a year.
3) keep covered in winter with a breathable trailer cover.
4) spray most exposed metal with a silicone type spray if you get snow where you live.
5) I use dryer sheets in all the cupboards and open spaces and have never gotten critters/mice/bugs.
6) Make sure the plumbing is PROPERLY winterized-I still have my dealer do it , especially if you have showers/toilet.
7) Use an interior humidity reducing product like "Drizair".
8) Remove the battery, store on a piece of wood, not the floor, and charge periodically during the winter.