I am picking up a few 20' sticks of #4 rebar to make anchors/supports for my trail snares, what length is best for anchoring snares? 18" or 20-24"?

I used 18" when I was in NV but up here I have trees. I also use 4' when there's no trees & just grass. Still put bout 18" in the ground than use the rest of it for the support wire off the top over the trail.

24”

If you are running long extensions(5-6’ or so) 18” stakes will work. They can’t really pump it straight up out of the ground. That being said, all my stakes are at least 24” long just in case I get in soft ground it’s nice to have the extra length then. They also double as water line stakes.

I use 18" rebar, or anchor to tree ,shrubs, or whatever is solid enough.

I use 2 16" stakes at each set. But they are cross staked.

Err on the longer side.

You dont have to pound a 24 all in the way in.

But its hard to pound an 18 in further when/if its needed.

Im making up 2 dozen today, going with 20" as a middle ground, our ground out here is about as unpredictable as a good woman sometimes its miserable to pound a stake and sometimes one tap it disappears into the ground. Im also running 4' extensions on my snares to help with any possible pumping of the stakes