A few years ago, someone started a thread in the instructor to Instructor forum in which he complained about the fact that as a new instructor, he could not get a job with any of the local dive shops. If no one will hire you for your first job, he wondered, how can you get any experience? People asked him what agency he had used for his new instructor certification. It was not IDEA, but it was another agency with very few instructors and no affiliated shops that anyone knew of. Once he revealed that, the response was unanimous. What on Earth were you thinking? Shops that are affiliated with the mainstream agencies are not going to hire someone who cannot teach for those mainstream agencies.
If you choose to become an instructor for such an agency, understand that you will almost certainly have to work as an independent, and your ability to work as an independent will vary dramatically by location. In some places, it isn't all that hard--local dive shops are happy for your business and will provide services to you and your students (gear rentals, pool time, boat dives, etc.). In other places, dive operators see independents solely as competitors and will not provide a bit of help. You said you manage a state=owned dive area, and that will probably make things easier for you. What state?