Hmm, I don't believe the math supports your position. It would take (ball-park) 10 trips with the helo to pay for one ER-qualified MD on call 24/7. Half to 2/3rds that again for one nurse or paramedic and 20 times that or more for the equipment. Two people on call 24/7 would burn out fast as I'm sure you'd recognize.
The numbers for an adequately equipped ER (equipment, personnel, and drugs) are high no matter where you are.
I encourage the existence of an ER but understand that depending on their capability they are not an end-all solution. The typical ER is a gateway to in-patient care. So, a full-fledged hospital makes sense. I'm all for it especially with a population of 20K+. Until then, what have you got? Nada. Sometimes small is more expensive but it serves two purposes: 1) immediate care to the needy and 2) incentive to reduce costs through increased capabilities/economies of scale.