A fairly safe reliable heat source for overnight in the ice fishing tent is a big woman on each side of you under the blankets.
There is a small stove called the Yukon stove. It was US military issue M1950 but you can still buy them. You just need a smoke hole stitched into your ice tent. The stove pipes fit inside the stove for transport so its compact. There is an optional siphon attachment for this stove that has a drip tube valve. The valve is put into a military style jerry can of regular gasoline. The drip tube drips gasoline into a fire burner that fits into the hole on top of the stove. I used one for a few seasons and just burnt wood. It has to be stoked more often because it is small but generates heat quicker on start up, especially in the morning.