Northern Michigan UNheated Cottage - Freeze Risk for WHIRLPOOL TUB??

Renovating our northern Michigan cottage bathroom. I wish to install a whirlpool tub. Noted that the pricier units boast 100% draining (pipes and motor). But more reasonably priced units which I prefer, e.g. Sterling Plumbing (Kohler's Economical brand), do not state this draining feature.

I will blow out the copper lines, but am wondering if water becomes residually trapped in these other tubs making them a poor choice. Any thoughts or experience on this. Very cold climate in winter. Thanks!

Will definitely freeze and be damaged. You can fill it with anti-freeze and run it for a few minutes prior to draining and shutting the place down for the winter. If you plan to use the place in the cold season, it would be a PITA and something I would avoid altogether.

Consider an air tub instead. These typicall blow-dry themselves after use, don't limit what you can use in them (oils, scents, bubbles, etc.) and, if you get a good one, are quite relaxing. They do not allow you to pinpoint the jet to a specific area, though. And, especially if you have visitors, won't be damaged if someone accidently turns the motor on without it being full of water. They are much easier to keep sanitary, a whirlpool should get monthly cleaning of the internal piping with some fairly caustic chemicals which probably wouldn't help a septic system (which you'd probably have in a cabin).

You'd still have to protect the trap, but that's easily accessed.