It really seems interesting to think a bit about keys in the WIF format. Let's start with base58. One behavior I noticed is that when you input the key in hexadecimal, the digits in base58 don't remain the same. For example, ...
hexadecimal aa = base58 3w

but

hexadecimal aaaa = base58 DzH

We can notice that the representation of aa isn't aaaa.

I believe that if we play around with this, we might get somewhere.