Make indoor box suitable for nesting

Hi guys, since the indoor box are free now, i would make some modification, i ve a lot of question i hope that i wont annoy you.
The box is 4 m^2 large, so i cant make the soil too deep ( i ve low budget), can I create a spot where the soil became deeper? will she use it? i should make it on the hot side? how deep should it be? can i have some pic of your s solution?

Should be at least 12 inches deep, that's the depth I have measured the nesting holes of my female leopard. I would imagine deeper for a larger tortoise. She might use it and she might not. No guarantees.

i think that redfoot need a less deep substrate she still lay 2 egg at a time