When your tank pet dies, I'm not clear how all of the other pets aren't going to get owned before the tank pet is ressed. Even then, if they don't die, I don't see how the tank pet will obtain aggro again if the fight has gone on for even a small amount of time.

Keep in mind that tanks have abilities for a reason. Many of these abilities are for overcoming unexpected events or even to deal with certain boss mechanics. A tank pet just isn't diverse enough as a general purpose tank. I'd guess that a very geared hunter could tank some of the ilvl 200 heroics, but no further.

Off the top of my head, some bosses that seem impossible for a pet to tank in your situation:

King Dred
Brann event
Mage-Lord Urom

GL though. I wish you the best in this endeavor.