Jcd has it right in my opinion.
What I've done in the past (with similar storage options) is to spray the day-lights out of everything with a rust preventative (I like LPS 2, or if you don't mind the mess LPS 3) then I cover the entire assembly with a plastic bag/s.
Thsi has worked for me, my $0.02

__________________
1992 500SEL 25K
1995 E320 40K
1995 SL600 120K
2002 JX8 Sport 43K
2005 Volvo S40 95K
2006 Isuzu NPR 304K (Frankencamper)
2007 Crown Victoria 150K
2014 Smart Electric 20K