Where do you put flexwatt heat tape?

ill do my best to help you. no do not put flexwatt tape inside of the viv because the animal ( you didnt specify what you had ) could come into direct contact with it..even tho you think its impossible, thermal burns are nasty and yes felxwatt needs air. 5 degrees isnt much but then again i dont know what animal you have so im going to assume its temprature delicate to be on the safe side. i would say get some aluminum tape and tape it to the bottom but since its wood, lets not. if all you tried isnt working what you could do is get the smallest avilable ceramic heat emitter and place it over the hide box, depending on how close the hide is to the top of the viv, if its too close it will over heat, otherwise it may be an option. sorry if it didnt help, i use flexwatt on my snake racks i dont have a viv. good luck