first, do you know what Popup Gizmos are or have you done much research on RV forums about hybrids?
if your answer to both is no, then look into PUGs or solar blankets for the top of the tent ends. PUGs have been used by popup and hybrid owners for many years.
i use the generic 5x7 solar blankets, which are made of the same material as PUGs.
using either in cold or hot weather, will help retain or reflect heat, depending on the season.
as far as heater/furnace, we rarely have electric hookups so we use our furnace. on the rare occasion we have electric, we use our ceramic heater and the heated mattresses.
using the solar blankets helps the tent ends retain the heat. also, using Reflectix in the tent windows is another way of retaining heat in cold weather.
i also suggest you do some reading on the Hybrid Forum at RV.net and at Hybrid Explorer's forum.
they are a much more active hybrid site that you'll be able to find out a lot of tips and tricks specific to hybrids.