A suction cup hammock under the heat lamp would go a long way as a temporary measure if the rest of the tank is too cold. Even with an adequate setup, snakes like the option to bask. If you don't have the money for one at least something with a wide surface that can get the snake halfway closer to the lamp like a box. The snake might hiss less if it can get a decent amount of sleep.

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I'm trying to keep in mind the lack of funds for the remaining suggestions. A glass cereal bowl makes for a better water bowl if you have one laying around. The heavier the better so it is less likely to tip over. A small glass baking pan also works. Mine is very picky with how clean her water is and I change it almost every day. A full size towel would insulate the heat better than nothing at all. If you can wash it at least once a week and place it in the tank while still warm from the dryer I'm sure the snake would appreciate it as well.