Another twist to Ro's rack

I want to build a rack sytem based off Ro's plans but with a few modifications. I was thinking that if I bought the flexwat heat tape, drilling a small hole in the back for the wire and actually placed it on top of the shelf, Then covered the heat tape with tile to keep the geckos from making direct contact, I would probably actually grout the gaps to make sure no toes or anything could actually touch the heat tape. Anyway how does that sound? Do you all think it would be safe with the tile covering the heat tape? I would of course monitor and control heat with thermometers and rheostats(sp?) or thermostats. Also I was planning on building it into double units with a solid divider down the middle and have the 11" heat tape in the middle, so the hot side would be 5.5 inches inside each adjoining cage. For example if I went 6 high, I would actually have 12 cages. It would probably be 5' wide with each cage being 2.5'x shelf debth (probably around 18") and probably 18" high too.. So What do you all think? If I am not making this clear let me know and I'll try to attach a diagram.

Im pretty sure you have to have some air circulation between the tape and the tile so you have to modify you idea somewhat...why not just run 11 in heat tape down the back?....if you are useing the lights tho you dont need the heat tape....the lights keep it right at 90 degrees.

I appreciate your input. Ro also told me he just uses 3-4" so 11" would probably get the cages too hot. Good thing I asked first.