This link shows the number of area coordinators, so you can see there is a rough correlation between state size/population/number of high schools/possibly historically high app rates. Your minimum would be at least 1 BGO/AC, and most probably a handful.
As to how many applicants each handles, I am sure that varies.
I will be interested to see what our resident BGOs say.
There are around 3400 BGOs. Generally, BGOs are assigned to one or more schools. The number of candidates can vary greatly among BGOs, depending on where they live. Some BGOs may have only one candidate per year (or even zero). Others may have 30. Just to be clear, that is the number of candidates assigned based on showing interest in USNA -- some of those may never complete even one item in their application.
No idea on total numbers, but I do know that the "density" of BGO's varies greatly. Some areas have a heavy Navy presence and there may be several BGO's in the same area and it is difficult to find BGOS , especially USNA grads, in other areas. I am in the Midwest, and have driven 2+ hours to present an appointment (a great experience, presented at HS graduation, class size was about 20 kids), and frequently have candidates drive that far for interviews.