There isn't a fire hazard if you use tinfoil, being that tinfoil doesn't burn well.

Dev, that moist hide will work fine if your snake will use it. It may not due to it being translucent, remember that they prefer dark hides, or you may meed to move it to the warm side. Best thing is to cut down on the airflow so you can maintain a stable humidity all the time. I am of course operating on the assumtion your using a screen top from the petstore, since I couldn't see the whole tank in your picture. Tanks and screen tops make a good start for an enclosure, but they require some extra work to truly make them suitable for reptiles.