Moving to a missile silo as prep is making a kind of strange bet. We know once the silos were targeted by multiple warheads, generally first strike ones trying to knock out the retaliation force. And these folks are better all those missiles will get different targets if something bad happens. Seems to me kind of the opposite of prepping.
I don’t think the abandoned sites that are privately owned would still be actively targeted.
One drawback is that most of the abandoned sites are easy to find using search engines or Google Earth. Being the owner of one I often run into people that find my site using those methods.
There silos will be their tombs, covered by hundreds of feet of volcanic ash.
Long term prepping has something to do with surviving radioactivty in air and water for a 30 year time span— minimum.