What I say I would like to do, or feel like doing and what I actually do are two very different things. First off, I simply get pissed off for about 5 seconds, probably mutter a couple curse words to myself and then move on and forget about it. Hunting time is precious and I'm to old to start any confrontations - you never know who you're dealing with. Last thing that I would ever do is create a situation that endangers the life of someone out there. You never know, a guy could have a medical issue that needs immediate attention and he may only have moments to spare to get himself to safety/help. I'm not going to complicate things for anyone.
I like to leave others alone and also like being left alone. I don't touch anyone's property - don't want anything to do with it. If I see a vehicle in a spot that I had hope to go to, I just turn around soon as I see them because I consider the area ruined for me for the day because I have no idea what was done in the area. There's other days for me. Ruined might be too strong or incorrect word.
Now here is where I back-pedal a little - if the the guy(s) were in a short dead end that is safe to target shoot in (with a good backstop like a dirt bank), then blocking the road does provide a good measure of safety.