New job, passing stealth, and bank can only put legal name. Advice?

So for context, I'm Canadian, trans male, and passing (though early on T, so nothing substantial like facial hair or a deep voice) and I just got a new job. It's a small, family-run store, and the owner knows me by my preferred name and knows neither my deadname nor that I'm trans. I don't know his stance on trans people.

The problem is, I haven't legally changed my name yet, and the bank is unable to put any name on my account or direct deposit aside from my legal name.

I don't want to have to tell my new boss that I'm trans, both because I'm worried he'll treat me differently or even fire me and (much less importantly) because I generally don't like that information being known. But it looks like I'm going to have to, in order to get paid.

Is there anyone else who's dealt with this and has some advice for what I can do? Is there any good way to explain it to him, or prevent him trying to use the legal name rather than the name I go by? I'll take any advice people have on this.