If you have at least a 20 - 30 amp circuit to your shed, that is plenty enough power to drive a small space heater, humidifier, light and multiple fa s. Just add up all of the amp ratings from the equipment you need to grow and make sure that’s no more than 80-90% of your total circuit amperage. That should be sufficient to keep you warm during the cold, but doubt that you will be able keep it going all winter if you are in the north. In Ohio, it regularly gets down to the single digits, and even below zero. Unless you are able to insulate, just give up or move inside for a couple of months.
As mentioned, tents are used in lieu of grow rooms. In an ideal situation a tent is located in a room that has enough cooling, heating, and humidity control to provide an environment conducive to growing. It is often referred to as a lung room. That is, the air going into the tent is preconditioned in the lung room.
I think most of us put a tent in a room and try to manage the room’s environment as best we can.
I would still recommend having a tent inside the shed. The good tent manufacturers have highly reflective mylar insides and also will provide a barrier for bugs. There are numerous reasons for using a tent, even if you live in a legal state. The point is that you can more closely control climate and other conditions, which will add up to higher yields and less problems.
Be real careful outside in SC @Doug79. They will bust the crap out of you for one plant in several of those coastal counties. My son lives there in one of them. I live in NC and it’s about as bad but the sherif is busy with violent crime right now and ignores us.
I personally went with a tent because it is a much smaller area i could control the environment. It’s much easier to dial in a 4x4 area than it would have been to dial in my entire basement. Not too mention the reflectivity etc