I have used Sawyer soak treatment and Sawyer spray for years now.
http://www.chinookmed.com/cgi-bin/item/03502
I hunt in Delaware and Maryland on the eastern shore. My relatives all get ticks on them-I don't. The only ticks I have gotten on me were dead when I found them.
Here is the reason you don't spray your skin-
not because it's dangerous.
From their website.
Is Permethrin dangerous to my skin?
A. The warning labels on the cans or bottles are often misunderstood. Your skin metabolizes, or breaks down Permethrin within fifteen minutes of contact with skin. Therefore, it is of no value to you as a personal protection insect repellent when applied to the skin. In addition, the EPA precautionary statement, "Do Not Apply to Skin" indicates that Permethrin is ineffective when applied to skin; therefore, do not apply to skin.
I have used it for about 20 years -different company and only lasted 2 weeks as opposed to 6 weeks now. I was hunting groundhogs and saw a tick crawling on my pant leg. after a few minutes it fell off, dying.
This stuff also repels flys, mosquitoes and chiggers. My cousin won't scout or go in the woods to set up deer stands except in the winter.
I treat my camo pants, shirts, undershirts, gloves,face masks, hats and socks. I use the soak treatment for coveralls and outerwear and I also spray my snake boots once a week.
I scout and wander around the woods all year long. No ticks ever!
And yes about 20-30% of ticks are active in the winter.