When I originally ordered my Blizzard through PPL Motorhome, I was told I could and opted for a heat strip too. Fortunately, I doubled checked the configuration and part numbers through Dometic themselves before anything shipped and was told it was incompatible.
After following up, I do not believe you can opt for a heat strip with the Blizzard.
It's for the better IMO, as the A/C fan is noisy. Hot air being circulated from the top is not ideal either.
I opted for a couple of these from Amazon. Cheap and work great. They have a low and high setting with thermostat, and are unobtrusive plugged directly into the outlets.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1