It's entirely possible, I'm already using overlay shaders to tweak the colors in levels. I don't really want to add a CRT effect since it kind of obscures the pixel art, and I think most players would find it distracting or hard to look at. However, I am considering including that as some sort of unlockable cheat, maybe if players find them as secrets they can turn them on or off in a special menu.
Also, what about your small tanks being designed more for fast-firing low damage suppression rather than direct kills? They could serve to distract the player, maybe two or three shots to damage the armor.
I like that idea! Very low damage weapons would be an interesting mix up. I'll definitely try it out when I get to implementing them.