How cold is it there now? I am in the same boat as you unfortunately, my new Bicals are not doing so well, blackening leaves and pitchers, only 1 week old now since arriving.
I too have the smallest one in a humidity dome. But of course I imagine you have it more complicated than I do, as even though it is cool season here, we don't get temps lower than 25C and humidity is still quite high, more than 60%.
My suggestion is do not use hot water, because the hot water if your climate is cold now, will just cool down in a few minutes or wihtin an hour, and your neps will still get cold. If you really need some kind of heating system, try a room that is heated all the time indoors, or if that is difficult consider using an aquarium heater. Using a covered Terrarium should help with the humidity.
I have a feeling that Bicals might not travel well, but hopefully both of us will find out that they will bounce back readily.
Good luck to both of us
TTFN
Arvin