I have two V-Tac type barricades and three smaller "Shape-Port" barricades for that kind of work.
Those have holes in them because NO MATTER HOW MUCH I YELL... people still shoot the wood. It's great training because they get to experience auditory exclusion due to trying to concentrate on the sights, the clock, and everything else... EXCEPT where the damn gun barrel is in relation to the sight...
Tanks you say... I spent 5 years on M60A1's and M60A3's... I'm quite familiar with tanks (60 series that is). My younger brother is currently a CSM stationed in VA... he was also on tanks and was a Master Gunner... he was on the Abrams though...