Looking for information on heated humidity tray for greenhouse window

[BlueWaterHorse]

I am new to the site and only dabble with orchids. I am planning a bathroom remodel and think I would like to put in a greenhouse window for orchids. The window will be on the north side of the house. I am in growing zone 8, so we see some freezing. I thought a thermostat controlled humidity tray might be a good idea, but I have no idea about how to choose one for my purpose. I hope to get some great ideas and information from more experienced growers.

[Royal]

A heated seedling mat may work. Check FirstRays, they might carry humidity trays too.