Hi there. I am not sure.

Iwas thinking a long box withhalf of it buried in the ground in a leaning position would have the same principles a hollow log in the forest would have.

I would have it kinda like a coffin, so when I open it up it would be a little easier to find the eggs.

PS I don't have any personale experience with breeding monitors.

its just a thought I had since I found lizard eggs in a wooden chest outside in the yard.