I have a SKU system for my products to personally identify them by category - then prodyct type - then product
So a typical number would be like this:
SA - 0501
DE - 0203
JE - 0504

Now I better remember their SKUs than their ProductIDs which is why I want to sort it everywhere by that SKU number field. However this is where it gets tricky:

For personal reasons I want the list to be descending by letters and ascending by numbers.
If I choose just descending I will get
SA - 0701
SA - 0501

And I want the opposite. So SAs first, but then 01,02,03 etc. like this:
SA - 0501
SA - 0701
Is that possible?