First off, I'm not an EM Coordinator, but I did stay at a Holiday Inn Express last night (and pursuing a degree in EM, have 5 years volunteer exposure ).

I would say you're on the right track, that's one of the first things I'd do!
Couple of thoughts come to mind (take 'em, or leave 'em):

• ESF's are usually representatives from agencies. You don't have a lot of them, so effectively, they must be covered by the next higher level of government. Also, elected officials usually don't participate in response. Think about the "correctness" of people like a Mayor running an ESF, etc. Separation of branches an issue? I don't know.
• You can assign multiple ESF's to a single entity
• Use Memorandums of Understanding( MOU's) to fill in your gaps, if you can.
• Use your county EM and state EM resources! They're there to help you succeed (I hope!)
• Do a Hazard Vulnerability Analysis [HVA] so you can find out what kinds of disasters/emergencies you'll be up against. You might find that all of the "important" ESF's are on one person!
• Check state law, you may be able to combine your efforts with neighboring jurisdictions, effectively creating a Regional Emergency Management Agency.
• Recruit more volunteers. Normally, big emergencies and big disasters bring commerce to a halt. Work probably won't miss your volunteers when they come to help you. Maybe get an MOU from key volunteers employers.

I'm sure some of this is obvious, and stuff you've thought of. If you want to toss around a couple of ideas, PM me. There are people I can ask too, one who has 40+ years in Fire/EMS/EM and has his own consulting firm.