some do have the optional electric heat, which can do just that... as long as you are on shore or gen power
the heat comes from the roof units, so the effect might be more minimal than if you just used a few small electric floor heaters, on low setting, like many of us do.
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada.... formerly Georgia, then NorthCarolina, now Alabama : )