I'd forget about a crossfit cert. Imho it's meaningless as the sole cert of a trainer as it's a weekend course which I've never heard of anyone failing.
That's not to say that there aren't good crossfit certified coaches out there, but my guess who's be that they were already good coaches before they did the crossfit cert.
Look into the cert offered by catalyst athletics maybe, or find a good gym of the type you'd like to open and see if they can offer advice, training or perhaps an internship. That way you get experience if the business management side of things too.