In my experience, it's absolutely possible to PuG Perilous (at least on PC). Of course, it's preferable to play with people you know, but you work with what you've got.
Safest way is to have a competent Barrier-er (i.e. casts Barrier BEFORE people are near death...one of the most common mistakes is only using Barrier when someone is on the brink). Even if the rest of the team has low dps or poor teamwork, well placed Barriers will greatly increase your chance of success.
In terms of strategy, understand team composition. Look at what other people are planning to play, and adjust accordingly (still staying within your comfort zone, of course).
A common example: someone picks AW. Great. OMGInvincibleSoEasyRun. Except that the AW doesn't have any real threat management, meaning when that Red Templar stabber or Venatori breakdancer cloaks and heads for your backline, two things happen:
1. your ranged dps/support is now running around flailing and not helping as much
2. the AW now has fewer targets to smack for barrier generation
This is one of the best uses of Barrier and CC. Once your ranged teammates feel protected, they'll be more willing to just stay put and pour out the dps, which reduces the amount of time you have to protect them, etc. If you're a Keeper with Chain Lightning, using it on a lone target charging or stealthing near your backline may seem like a waste of a great skill, but might be the difference between a clear and a wipe.
For tactics, the most important things are to understand where to stand and who to target.
Know when to group up and when to spread out (clumping on your barrier caster is usually a win). Be aware not just of who is trying to kill you, but who is trying to kill people near you as well. There's nothing sadder than dying to an arrow meant for your tank. Also, if you see a Bear or a Gurn (rhino thing), just run around like chickens. A single Gurn charge can and will wipe your team if you stand together.
Prioritize your targets. Focus down threats like the stabbers and dancers mentioned before, and anything else that would give your particular team problems. If it's something dangerous but really tanky, kite and CC it until the enemy archers are down.
I can't emphasize enough how important CCs are, particularly in Perilous. A frozen or knocked-down target is one that's not harming your team. With the way threat works (or doesn't) in this game, having an on-demand way of protecting your squishies is crucial.
Hope this helps, good luck!