I'm not too sure I know what's going on - there in Shelton, WA.
The plants are in a fish tank which is wrapped in bubble wrap. So they are really covered up, day and night, right? It really sounds like they need some fresh air.
The outdoor temperatures must not be very warm if it is dropping overnight to the 30's, INSIDE the greenhouse. In fact, it sounds down-right COLD there are the Olympic Peninsula!
Winter hardiness zones don't "translate" very well from one location to another. Since they have to do with winter temperatures and not growing conditions, they may not mean too much for tomato gardening.
Western Washington has a loooong growing season, it is true. However, there isn't a lot of sunlight and not much heat . . . during a normal growing season. Sunlight and warmth mean quite a bit to a tomato plant.
This map probably doesn't extend into Texas zone 8 but it gives you some idea of what the yearly warmth one can expect in western United States.
Growing Degree Days, base 50 What you see is that in terms of warmth - most of western Washington looks more like Montana than Texas !!
I can't expect to get a ripe tomato off a volunteer that has self-sown outdoors. I live up there at just barely the 2,000 growing degree day border. Most of western Washington isn't any warmer than that.
On the other hand -- look at western Texas.
Steve