Underground or NE covered RV storage/

[blueblood]

I have friends from AU who spend the legal 6 months here each year. They store their RV and toad  in a covered facility in Yuma, AZ until they return. This year they are ending their travels in NE US and Canada and they would like to store there so they could fly back to there and resume travels from that point. They are looking at an underground facility in PA and wonder if any one has any info on these types of places as to mold, mildew, rust, etc or if anyone knows of covered storage elsewhere in NE.