Thats fine. That is exactly what I did to my 40 gal breeder for my Burm. As long as the hole for the heat lamp is not in direct contact with the heat it will be fine. I cut the tape about 1/8 in bigger than the lamp itself so the edges are not even touching the tape. Then instead of cutting a big square for ventilation, I just left about a 2in gap all along the back of the lid.

The only real problem with duct tape is it will not stay on there very good. So make sure the edges were overlapped enough. Dont put it on the underside of the screen though. It will quickly come off and the snake can get stuck to it.