if you are using one of those flat kind of zoo med under the tank heaters here is what i did in one of my tanks. i had the same problem as you. now keep in mind you dont want to cook your animals so if you do this you need to know whether you animals is a burrower or not and you really need to keep and eye on them at first. i use similar bedding to what you use. what i did was move the heat pad to the inside of the tank and placed a piece of astro turf on top of it. then i put a very thin layer of bedding on the top of it. they love it and i could definitely tell a difference in there body heat when i pulled them out afterward. if the tank is 55 gallons they have plenty of room to go to the cool side if need be. i have had this set up for several years in this tank and have recently replicated it in another tank for my new little ones and they seem to enjoy it also. just a thought.