character class that has some mandatory and optional members

No, character classes are sets

What would be your way to match ...

Tokenize, naturally, match things you know to match, then match what is left,... instead of looking for what you don't want, match what you do want , like pure numbers

You can refine your search once you have a bunch of tokens

see Re: Help required in find command. (read parse file tokenize m//gc)