You can simply swap between the same two things. After seeing that was an achievement I knew it'd eat at me if I got a big combo and dropped it so I simply bounced between two platforms and got it pretty quickly.
Also, the achievement doesn't pop until you land so don't be worried when it doesn't immediately pop up.
Edit:
I'm decently far into the game (I'll hazard a guess and say about halfway based on forts/regions) and the game hasn't done anything anything to prompt those other three exploration things to collect but I did manage to come across a place to tag on my own during a mission. I would imagine it'd be a common tag spot for people but I can't remember the specifics if I jumped up that way on my own or if the game pushed me in that direction. The tag spot was a big billboard with something about "Pay to have your add here!" sort of message.
Still haven't come across an eavesdrop or the viewpoint thing, whatever that one was called. But generally I've been fairly focused on story missions and doing some side missions. Skipping most the challenges, too. Figured I should get as many of the mechanics out of the way before I focus on the rest. After the
does the game introduce any more mechanics? A simple yes or no is fine. And what I spoilered isn't a story spoiler at all, just a description of a mechanic.