Another idea regarding BMP-3 especially. Make sure to use them not with only the two crew members onboard. I usually put a team of two that I detatch from any infantry squad (usually I tag out of the squad a "scout team") one of those two soldiers will occupy the commander's position in the BMP-3 and will surely improve your spotting ability. It's a costly trick but can be useful if you need to use your BMP-3 as a bronegruppa.   Side note: remember that MTLBs are the most "mole" vehicles of the entire universe.