Thinking about a tubeless set up and wondering what rim tape width to use?
Do I just cover the spoke holes or does the tape need to match the inner width of the rim?

Depends on the rim but better if it’s full width as the tyre can them seal against the tape.
Loose tyres can require a couple of wraps.

Internal rim width plus a few mm to account for the profile of the rim. This means you are only sealing tyre to tape.