If the thermometers on the wall are so high up your snake can't reach them, then they are doing you no good. The top of the tank ambient air temp will not be the same as the near-ground level (heat rises remembers), if you meant the velcro / thermometer is so tight...well never underestimate the power of a snake. You'd be surprised at how easily they can knock that gauge off, even a young one. Especially if you think they can't. They'll do it just out of spite
Anyways, OP: Though some might take risks, I would never, ever suggest taking the risk of putting anything sticky in your tank. You snake will thank you later when it's not missing a large portion of it's skin / scales.