I have stored my campers outdoors for several years. Properly winterized, cannot imagine nor have I had any problems (even with serious snowstorms that we get sometimes here in the midwest) . I could not imagine paying $900 for a season given that would cover over 3 years of all year storage for me.
Jack of all trades - Master of none
2012 F350 CC DRW - 6.7L PSD
2014 Sabre 36QBOK