My box heats up quickly and I only use (3x) 100 watt bulbs. I never concerned myself with getting the bow too hot, but I use 1" thick foil-backed insulating board so it retains heat well.
With that, during my last glue up I noticed that it didn't get as warm as I wanted it to be - not by a long shot. I panicked then read as much as I could find on the web about Smooth On curing at near room temp. That bow is fine and shoots well; glue lines are tight and there is not perceivable difference with the glue's properties from any other bow that I have built. I am waiting for a couple more layers of Tru Oil to dry prior to posting any pictures of it.
I'll have some more Smooth On at my house on Wednesday and I intend to glue up my daughter's bow that night. I may not even put it in an oven, I'll just keep it in the form longer.