This isn’t well thought out, but I’ll offer something to shoot at…
I roast outdoors and am at the mercy of the elements/temps. In SE Arizona winter can be a little uncomfortable so I have to pick my days and roast in the afternoon. A space heater would do no good. For me, the real issue is summer which means being up early with a plan already in place for what I need to do.
Winter roasting means a significant ambient difference from summer roasting. So far I have had no real issue except the roast stretches a little. The Bullet does a fair job keeping up with the heat loss when roasting 600 g. I think I’d have a problem if I were trying to roast 900 g.
I had thought about putting a cardboard tent over the roaster body to slow the heat loss through the sides of the roaster, but I suspect the bigger issue is the cold air drawn into the roaster by the exhaust fan. Can’t really fix that without an enclosed space.