Load whatever you carry for defensive loads for humans and leave it at that. I carry a 642 from pants on till pants off, and live well out in a rural area. I carry five CorBon DPX 110 gr. HPs in the gun and five more in a speedloader. I'm not worried about snakes. At all.
As far as hiking through the woods goes, the snakes live there, you're just a visitor. Leave them be, unless the snake in question is a copperhead that takes up residence under your front steps at home.
If you aren't walking barefoot it isn't likely you'll get close enough to a snake for it to bother you- snakes sense vibration through the ground and will usually flee any approaching large creature they sense approaching. If you're that concerned about snakes, just walk with normal footfalls and most of them will be gone before you get there. And the ones that don't manage to get away- if you're watching, you'll see them before you step on them. No need to bother them if you see them first, wait till they move or go around.
And if you step on one before you see it, shooting it at that point won't do you much good anyway, if it hasn't bitten you. In the event of a bite, you might need the carcass to identify the snake. Best bet is to watch where you put your feet/hands/butt, and try to avoid unpleasant encounters with all wild critters, snakes included.
ADEE* works best for humans, it's the best approach for reptiles also IMHO. You cannot create a life, any life - you should be mindful before you take one. A human may attack you out of greed or malice- snakes will not. A snake bites in an attempt to defend itself from a perceived attack, or in an attempt to disable something it perceives as food.
lpl
*ADEE = avoid, de-escalate/disengage, evade, escape