How long can I stay without becoming tax resident

If you want to stay in France longer than 90/80 you need to apply for a visa. It’s not complicated. But depending which visa you are able to get you may not be allowed to work.
Saying you need to register and you need a residence permit is missing the point. What you need to do is follow the rules. France will only give you what the WA says it has to give you, not what you think you need.