Quick question about temps.

[Chandra2]

I know the hot spot is supposed to be 130-150 and ambient temps around 80-85 on the cool side. But what about inside the soil where they dig?
I just got about 15 inches of topsoil, sand and yard dirt in the cage but it was around 40 degrees.Ive put some brooder lights above the soil and have been mixing it up to bring up the temp. before I put him in.

Also should I pack down the soil?
I will have it almost 2ft on one end and only about 10 inches on the basking end probably less if I have to pack it down is that about right for now?

I can add a bit more if needed but it will take time to bring the temps up again.