My room is a colder that yours (68-70) I have run 17" flexwatt for cool end temp control. You will need a good T-stat if you plan on running a dual heat system, on off ones in my experience don't deal well with cool rooms they do much better in warm ones the overshoot and under shoot too much. (5 degrees on each end) I'd recommend a herpstat II as it is the best price. I also insulated the bottom sides and top of the rack to help.