As a former tank crewman I'm not sure if taking cover next to a tank is really a great idea. The crew of the tank probably have no idea that the squad is there. The driver, gunner and loader certainly won't unless the commander has seen them and passed the information on. The commander may not know that they have moved there unless he has seen them or been messaged by another tank commander in the platoon/troop. In short, a 'Left stick' order from the commander to the driver will result in a messed up squad.
Tanks attract the wrong king of attention, the kind that squishy sacks of water don't fare too well against. On top of that, have you ever stood that close to a 120mm gun firing without ear protection? I have on a training range and I learnt not to do it again!
With regards to cover, in the end I think it's more of a psychological effect than practical.