I think you could very easily install a tank heater pad and resolve that issue.A quick update friends, we reached a lot about Taxa Mantis, it seems that fits us very well. Except water tank is not available for use in winter, but people saying the cabin is warm enough for 10- 20F with or without pop up. More than one owners in their FB owner group used it for ski trip, so might work for us too.
We actually like the design ( milk crates for storage, steel frame with hook up points everywhere, modular functionality and modern/mcm aesthetics) .
As far as we research, the leaking problem should be invested intensively and solved over the past years. It might not be on par with Kimberley quality wise, but the price point and functionalities suit us very well. Also we have a local dealer. And it’s light and not too bulky for either towing or towing. We are seriously considering it now.