Hey and welcome to the forums!

That's a good question. Personally I would think that if your four hunters can do enough damage before the pets die, you may be okay with them tanking as long as you don't have your hunters pull aggro. I have a 5x hunter crew and haven't done much with them yet but I'm planning on getting three of them bears so I can tank instances with them. I would bring a healer along in your case, maybe a paladin. It would be cool if you could find one with two sets of gear so he could either heal or tank if necessary. That's just my two cents on that but again, I'm not speaking from experience. Either way, let us know how it goes and good luck with leveling.