You may be taking the wrong approach.
Consider this, If Brown's model is accurate then:
EITHER
the freexing that killed the mammoths and rhinos is directly related to the layering of rock so no area is affected by both
OR
there were many mammoths and rhinos killed and the frozen ones are just those that happened to remain near the scenario.
In the first case you should be looking for a simple relationship between the two effects. If you have to look at compications then it probably isn't the case. In the second there ought to be rather a lot of deeply buried mammoth fossils.
And given that we do have fossils of quite delicate creatures - they're rare but they do exist in areas like the Burgess Shale - then I don't think there's a good case for assuming that all the mammoth remains would be destroyed. And while we have only searched a small fraction of the Earth's rock for fossils we probably have a good enough sample to conclude that it is very unlikely that there are Precambrian mammoths.
Which gets on to another issue. It should be possible to get some idea of the order we should expect to see in the fossil record from whatever mechanisms Brown invokes to explain it. Since this is one of the big problems for YEC it is an issue that can't be ignored.