^Sure, you are right. I didn't say that noone should run two tanks for such a big party. I've just said that running two tanks could lead to really awkward situations and as such - in my opinion - it is not the best idea, especially if you have other options too. Of course, if the OP doesn't want to bust Comrades or give a super-heavy tank to the party, then he could run two tanks, no problem. But he has to pay attention to the problems this solution has, namely the phyisical separation of the party and the lowered need of cooperation. 

Man I walk away for a day or two and the thread explodes.

I'm not going to go with multiple tanks, period. It's not because of the logic of having multiple tanks but rather because it would go against the whole concept of the campaign. I want a single Russ to be their roaming base of operations, their home, and it's constantly under attack by insurgents taking advantage of an army ran razor thin. Adding a second Russ greatly reduces the inherent dangers of being a lone tank as you have someone watching your back. Sure, I could just write encounters that would put BOTH tanks in danger but it really lops off a lot of neat ideas I have for the group. This Russ should be a privledge, not a given, and I want the players to really feel the value it has. Ideally I want this game to eventually boil down to harvesting tread links and other nessesary bits from blown out vehicles littering the tight alleys, with the constant fear of ambushes while they try to steal some fuel or ammunition.

I've pondered about dropping the comrades, but I think that takes a lot of teeth out of the squad considering some of the added abilities. Since making the thread I've been scribbling ideas and scratching them out and I think the most logical approach to take, in order to preserve the tone I want, is to remove the sponsons from the Russ so it's just the hull mounted guns and allow two players and their comrades to operate the vehicle and its weapons. The remaining four players and their members will have to tread lightly as being near the tank might open them up to fire, so they would be encouraged to form a tight unit that clears out buildings scounts ahead for the Russ to ensure the path is clear. I think that here I can steer the group to consider their tank more of an objective than an asset and really drive the missions and personal goals to helping the tank as much as possible.

I'll fiddle with it some more and see what I come up with, but I'm going to agree that multiple tanks isn't the way I would want to go.

What about a Malcador Defender instead of a Leman Russ? The two tanks are fairly similar, but the MD needs like 10-12 guys to crew it. 

Here, take a look at it:

http://www.forgeworld.co.uk/Warhammer-40000/Imperial_Guard/Imperial_Guard_Super_Heavy_Tanks/MALCADOR-DEFENDER.html