A heater is perfectly safe to run in a tent, i've been doing that for years. You can set the heater to come on and off at certain temps, using one of any million types of controllers out there. You have to be careful when you water, and little heaters will only last a few seasons before needing to be replaced, but running a 200W heater in a tent is no more dangerous then running 500W of light. In most scenarios, the light itself will keep the tent more than warm enough during the light cycle, to where you will actually need to exhaust warm air out to avoid cooking the plants. But during the night cycle, your plants will get cold and will need some additional heat if your basement drops much below 70F.
If you are really nervous about adding a heater to your tent, then the next best move is to setup 2 tents, side by side, and alternate the 12-12 light schedule so that one tent is always on. Then pump the air from top of one tent to the other and back again, creating a loop of air going between both tents. That way, the tent that is on, will keep the tent that is off nice and warm, back and forth.
i've used both heaters, and recirculating air from tent to tent, to grow in some real cold areas, with very little added energy, and had great results. If you ask me, i'd rather put my tents in a cold area and heat them up in this manner, then growing in a hot area. its much easier to keep the tents at a proper temperature, if their surroundings are colder then what you want inside the tent.