I was there for a whole week beginning of July and the I'd rate it at 3 b/sqft (yes, this is a very scientific measurement!) at the worst areas. The bug concentration was very different depending on the current weather and the location.
I had a hell of a night at Pogy Pond where they kept me up as I buried my sweating self inside my sleeping bag and slept with my headnet on. Hiking that day was also buggy, but only near streams, bogs, lakes, etc. Same deal at Little Wassataquoik Lake, but this time I smoked them out with a fire.
A lot less bugs on the South side of Katahdin during that trip.
I think you should be fine with the headnet and the Bens - reminder, the 100 is meant to be used on clothing and gear, not skin.