Heat Tape and Rack Predicament...

So, after much time of researching and such, I've decided to build my own ball python rack! Currently I do not own any snakes, but I will be picking up a few at the next Repticon I attend (: My problem is this: I'm not sure where to place my 4" heat tape (which I am ordering later) on my rack. You see, there is this little "dip" at the back of the rack where I should place the heat tape, but I'm not sure if it's safe. I've attached a few pictures so you can see what I mean.

http://i1209.photobucket.com/albums/...psb6445a31.jpg
http://i1209.photobucket.com/albums/...ps1fd27973.jpg
http://i1209.photobucket.com/albums/...psb17231e8.jpg

Ironically, the "dip" is exactly 4" wide, so the heat tape would cover the entirety of it. Do you think it would be safe to install the heat tape over it, or maybe right in front of the dip? (which would be about the middle of the tubs) I want to make sure my rack is as safe as possible, so any and all opinions are welcome!

I would think it should be ok to use the tape over that.