Twin Peaks is WSG on speed. They're very much alike, but they aren't identical.
To begin with the flag areas don't have the excessive amounts of attached areaas where you can run around and hide. They also lack the opportunity to back into a corner at the very place where you want to dump your flag.
TP is also smaller than WSG. Swapping between defence and offence is a lot faster.
All in all this calls for a slightly different strategy for the PvP tank.
When you collect the flag, ride in through the front door, but exit through the side entrance. Don't stay, just grab the flag and get the hell out.
When returning home I personally prefer going back through my front door. The reason for this is that I've seen too many abyssmal accidents result from having your team split in two groups because you're trying to sneak in through the side entrance together with your escort.
Going home through the front door means hacking your way through the choke point. Again this isn't as bad as it sounds if you have solid team mates. You take fire because the flag you carry aggroes just about every enemy in sight, and your healers keep you up, remove snares and occasionally Holy Leaps you a bit closer to home. During the entire chaos your escort gets the opportunity to give enemy healers a hefty gift of hurt.
Obviously, if your team sucks, then going through the front door is suicide, but you're likely to get stomped all over anyway, so it really doesn't matter all that much.
Well back at home you'll want to stick close to the flag until you have incoming enemies. Then you should move to a corner which can't be targeted from the platform above you. That way ranged enemies have to get down on the floor where they can be targetted by your own melee. Make sure your healer stands close to you as well.
As with WSG, hiding above the flag is taking a huge risk. You can be separated from your escort and go down in seconds.
TP also differs from WSG in another way. Three tanks isn't all that excessive in TP. The reaon is that even a short delay can be golden. If you have three tanks in your team, then having one suiciding by crashing into the enemy train heading for your flag is good use of your money. If the enemy dismount to kill your offending tank (and they usually will) then you've just split the enemy into two separate groups even before they collected the flag.
In the best scenario this results in a slug-fest when your own flag carrier returns with their flag and they're still busy collecting your flag. You can afford going all out aggressive here, because even if you lose your flag by getting killed you still have ample time to collect theirs long before their flag carrier can return back home. Obviously you could get lucky and down most of their team before they can exit the building, and if that happens you're very likely to kill their flag carrier during the next wave of combatants incoming from the grave yard.
Just as with WSG the battle will usually boil down to you waiting at home with the enemy flag while your stacks of damage debuff tick away. The difference is that incoming waves of enemies come quicker compared with WSG, and an offensive team have a far greater chance of going defensive due to the shorter distances involved.
In the three tank team (or a two tank one with a squishy collecting the enemy flag and returning for a drop off) this means you want one tank being a major PITA on the bridge separating the playing fields. If that tank and a healer can keep three or four enemies busy in the middle you're likely to have superior numbers where it matters. It also slows down incoming attacks.
As for the flag carrier back at home, you'll have to take much higher risks compared to WSG. You're a weak damage dealer, but a damage dealer still. During enemy waves you'll simply have to take an active part in reducing them. This will mean you risk being CC when your own team kills the enemy flag carrier, in which case they'll pick up the flag before you can capture it. If your healer is a priest this isn't a problem as long as you have spoken beforehand. Have your priest healer heal you from the capture point and Holy Leap you immediately if your own flag is returned home. Obviously never fight out of reach from your healer.