When you're trying to get hired, talk the talk you know about the problems the company has, not about all of the skills you have. If you're able to focus the discussions on how a subset of your skills provide lots of value to the company, that's what's going to get you hired. Show that you know the domain that the employer wants to see. Definitely mention your other skills, but don't make them the focus of your interactions in the hiring process.

Then, once you've been hired and start working, you will naturally use your other skills to add value to the company. After you've been with the company for a little bit and have shown your other skills to also be valuable, that's a good time to discuss getting more formal authority in other areas and/or a raise to compensate you for the duties you've taken on.