I don’t think I’ve ever seen a lay-down gun safe that held more than 1-2 guns. What I’ve seen seems to be designed for under the bed storage with side access, so the number of guns is limited by this factor.
How many guns are you needing to store?
I, too, would be worried about moisture, AND with this wet year, ANYTHING at ground level or below is prone to water entry unless this house sits on top of Mt. Everest.
Is there no chance of a boring old “safe in a closet” solution?
I even know one guy who, for lack of a better place inside the house, has his gun safe in the garage. He did a little extra work on his garage by replacing the window with shatterproof glass and the side door is reinforced steel with a steel frame. The safe is hidden in a cabinet and he runs 2 Golden Rods in it. Never had an issue with moisture or 2 legged vermin.
Grouse