... if you're gone from the cabin for 3 months you will not have to worry about coming back to dank water, because you will have drained it.
This would work for a plastic tub, but not a wooden one. The wood tub needs to be filled at all times or it will shrink. That may mean several day's work getting it to swell back up enough for it to even hold water. Also, repeatedly drying out a wood tub can lead to a warped board or two which will not seal up again.
If this tub is going to sit for months at a time, plastic might be the best way to go unless you hire a service or ask a neighbor to look in on it from time to time. It will NOT need to be tended to very often when the water is cold if it has a good cover. Once a month should be fine - perhaps an inline feeder might even work - but you don't want to over chlorinate a wooden tub.
A plastic liner on a wood tub might work, but that adds other problems.
Doc, where are you?