I worked for the US Forest Service in Alaska and we always wore long sleee shirts and long pants. We also wore metal hard hats. Have you seen the tape attractant (yes attractant) that you can tape to top of ball cap, etc for black flies and gnats? They stick to it. You can find it at Cabala's, mostly used by early season deer and turkey hunters. Have you tried Orvis or similar Buzz off shirt, hat, etc? I have two Orvis long sleve Buzz off's and they appear to work for me. I also like the OFF brand wipes. After wiping down back of hands and face I put the left over wipe under my hat.