Could hacking my Wii cause an IP ban?

No, since Nintendo's online services were taken offline back in May 2014. However, if you're talking about an alternative service like Wiimmfi, so long as you aren't cheating online, you should be totally safe using backups online

 

Outside of what is usually termed a film plot in security circles then as the official Wii services are defunct (or all but) then no. Even if they were up it would be a stretch for console hacking to see such a thing.

The earlier stuff with an early stage hacker being banned that you might be basing this on variously turned out that the other device was possibly used to test a hack and was not so clean as first thought, that or as said hacker posed a real threat to Nintendo where if you are asking this sort of question you will not be.

 

There is no online to cheat on in the first place...

There's Wiimmfi but if you get banned that just means you won't be able to play on Wiimmfi servers anymore and obviously... the ban would only apply to Wiimmfi

 

No it wouldn't be a problem, but there's no reason to use the Shop Channel anyways since it's been shutdown.

Basically there's no way a modded Wii could affect any other Nintendo online services.

 

you wont get banned on wiimmfi unless you cheat, if you do get banned wour wii wont get banned because it wiimmfi