I’m not sure if you’ve already completed this, but to those who haven’t it’ll surely help as I just finished doing this after a shameful amount of attempts. You HAVE TO kill every guard in the area beforehand without going into alert mode. After that, make sure you have sticky dynamite and anti-tank grenades equipped. Stick two sticks of dynamite on the tank (without it detecting you, fairly easy if all the guards are eliminated), then one on each heavy gun. After, throw one AT grenade bundle directly at the tank. Right when those grenades explode (roughly 1.5 seconds), trigger the dynamite. That must be timed perfectly; you will be prompted that the objective was cleared right after doing this if done correctly
Hope this helps
You don't need to kill every guard (although that does help).
If you do it right, you can go directly down the center, plant your dynamite, throw your anti-tank grenade and immediately use the field gun to blow up the last objective with the fuse finally blowing you and the last objective up before any guard spots you.
