Are my specimens buried deep enough?

My taxidermist gifted me unprocessed deer skulls with the racks removed. Long story short, he gave me more than I anticipated so I had to bury them because I didn’t have any other place to put them (typically I freeze some and macerate some). It’s been chilly here and it’s a little to early for smell but I’m hoping someone has some advice for reducing odor of burial for processing or can reassure me that I’ve done enough to make it less offensive.

Here’s what I’ve done so far:

• The skulls are wrapped in light linen cloth to reduce discoloration.
• They’re buried about 1-1.5ft from the surface and have worm castings mixed in to try and help with decomposition and microbial growth
• They have a light layer of hay underneath of them and have a chicken wire cover which was buried over them.
• Theres a small layer of charcoal bits to try and help stop odor.
• On the surface there’s another barrier of wood lattice with concrete blocks and this is covered with a layer of hay and topsoil creating a mound that’s probably another foot deep. (I can always add more soil to the mound?)

I’ve read that I can use lime (calcium hydroxide) to reduce the odor but I don’t want to halt decomposition, is there a healthy balance?

I’ve done burials in the past and typically keep them shallow but well fortified to let the bugs have a go at them too, but I opted for deeper with the skulls because it’s more than I would usually bury.

Any advice is appreciated!