I do agree that trenches seem to render opponents a bit
too invisible - Though not being on the ground in the same location, at the same time, and looking at the same trenches, i can't really comment on whether it's realistic or not..But it's indeed quite annoying.
One thing i've found useful is, (aside from the attack-ground command for vehicles which can also be restricted to MG fire, just select one of the MGs and you'll save the rounds for your main gun.), using air support when you begin your advance, they generally reveal all enemy positions and depending on the aircraft can devestate a trench position, or perhaps take out a couple of AT guns as they pass over.
Other then that, just keep your tanks far enough away that the AT-rifles cannot penetrate and you should be able to scare them out of the trenches prior to your infantry getting in range. Then as they flee they are easy prey for your tank's MGs and infantry small arms fire.
This game requires a lot of patience and quite a bit of saving/re-trying with new tactics. You'll get the hang of it.
