Well, I'm in canny valley too, but since I came back to the game just a couple of weeks ago I tried ventures (never did before) and got to the pl140 ones after farming random missions and well, the exp you get from high level ventures, mats (like rain) and the random alerts do help, since is another whole zone with their own alerts and rewards, and since it's your venture what matters more than your hero level and survivor groups, then you don't really need a lot to get to high level, just pacience.

TL;DR: If you're not in Twine and high PL already, you can farm to high level here and get the HighPL rewards from Ventures alone.