I think you will be cramping Brad's Black Heart and Red Brandywine
Heart in a 7-gallon container. 15-gallon is ok for these big-fruited
mid-season varieties as long as they have enough calcium and consistent
water levels (BER is a potential problem).
We had a slow start to the summer, and I got about 3 fruit from
Brandywine Sudduth last year in an overall cold, rainy summer,
growing it in an 18-gallon self-watering container (so about 15
gallons of root space). Brandywine and Stump will have a difficult
time ripening fruit in a short summer, even if the temperatures
drastically improve.
This is our problem:
http://www.ipm.ucdavis.edu/WEATHER/ddconcepts.html
We need exceptionally warm summers for those big-fruited, mid-season
tomatoes to do well. Since we already lost a month to weather off of the
North Pacific, it will take a miraculous change in the weather for the rest
of the summer to provide enough growing degree days for them to
set and ripen fruit.
Grub's Mystery Green is perhaps the earliest plant in that list, aside from
the cherry tomatoes, so it should still produce regardless of the short
summer (so maybe leave it in the raised bed or a 15-gallon container
and give it a spot with good sun).