I think it's a terrific idea. I'd love to get into a group that can give me better rates and probably better coverage than I have now. I saw my health insurance go up $50/mo at the first anniversary date and the same again 6 months later. Second anniversary is approaching fast. There is no end in sight. It's also important to have insurance that travels where you do, whether you travel for work or change your residence. Do you know that many plans are local or regional, and that if you move out of the area you need to reapply? If you have developed a chronic condition, you may be unable to get insurance at any price.
That said, my 2-person operation once had insurance for my secretary through a professional organization. They ultimately got out of that business because it became a tremendous hassle. Because she had health problems, the only individual policy we could find after that cost $750/mo (it's complicated, but a 2-person company in Tennessee must have both people insured in order to get a "group" rate--then that rate is based on the health status of the two individuals who form the group--in this case I was insured under my husband's policy). At any rate, one of the problems is that such professional groups tend to accumulate the less healthy individuals, which ultimately drive the premium costs up a lot. If you have a large population of 40- and 50-yr olds, the 20- and 30-yr olds are going to find individual policies much cheaper, so won't tend to join the group. The young healthy folks are the ones you need to keep everyone's rate down. On the other hand, the avoidance of paying for COBRA becomes compelling after the first time one is laid off.
How are you going to limit the group membership? I don't do field nuke work--all of my work is in the office (I'm not even badged). Will you set up a membership organization and charge dues? Will you have underwriting requirements that would prevent high-risk individuals from joining the group?
I encourage you to look into the possiblities, but I suspect you will find it more challenging than you expect. Do keep us informed about what you come up with.