Double the distance atleast
I'm not totally sure why there's Tethering in this game. But I can only imagine it's because of technical issues.
For example, if 2 players, in a co-op, end up liberating 2 neighbouring towns, which video gets played first? The game simply wouldn't know what to do and before you know it, you've broken the game.
In FC 5, you have videos of people moving in to a town you've just liberated. Or Nancy, doing her physco thing on you, etc.
But with Wildlands, there are no videos. You just go in, take out the enemy and move on to the next target.
My Son & I are getting in to co-op-ing on FC 5 and we work well as a team. The problem we having with the tethering is with air drops, using the wing-suit. My Son has to slow down with the parachute because he's gone too far. Like many others, it's also an issue when it comes to one sniping and the other going in. The air cover ain't too bad of a problem, within a town, as we use helicopters.
Personally, I think the tethering needs at least doubling. This way, players can enjoy the game more, while sticking to the rules of the game.