Lamp that works with zen habitat?

I recently purchased an enclosure from Temu that closely resembles the Zen Habitat enclosure. However, I'm having trouble figuring out the best way to position the heat lamp. When placed inside the tank, it's way too close to him, but when it's outside, it doesn't provide enough warmth. Could anyone suggest a heat lamp that would work better or (preferably) offer advice on how to solve this issue? I'm open to any constructive criticism to make his overall setup better as well!