DEBIVAN

We are considering underground storage this winter for our motorhome this year. Here in Southwestern Pennsylvania all of the underground facilities have an 11' height limit for their conditioned area therefore we would be limited to their unconditioned areas which still has a constant temperature of 52 to 56 degrees with a 65% humidity level. Everything I read says to keep the humidity between 30% and 50%. Can anybody share any tips of insight on this subject?