I've live in Tahoe. Relative humidity is 30% most of the time, really dry. Different world. You'd be better off leaving in the water than hauling out.Keeping on a dirt floor to prevent shrinkage. Never heard that before, having had a Century 17 resorter (woodie) kept in a wood floored garage all winter on a trailer.
Come spring every year would nearly sink for a day or two when put back into Lake Tahoe while she swelled up.