Snakes are nothing to worry about even in the summer but nonexistent (above ground) in October; at least in the area you mentioned.
The Chikamin/Mad Lake country is well trailed and open for motorized and mountain bikes so access is pretty easy. If the deer are starting to move (snow at 5000 feet), you might do well to look at migration routes such as passes on a ridge such as hiking up trail # 1539 to meet the deer coming down the Chiwawa River.
Rather than looking for easy country to walk through, I would seek out the most rugged, vertical ground you can find. Either "still hunt" or just sit there and glass.