The rammer helps. I believe but do not know, the perk Brother in Arms crew skill helps, Adrenaline Rush:but only when @<=10% health, not so useful in one hit wonders, but can get a lot of work done in the right tank. If Brothers in Arms in fact increases reload, then improved ventilation would as well but not applicable with the Marder, just generally. You might have to adjust your play style to include displacement after a shot. As you get better playing higher tiers so too will your opponents. They will be able to hit you even when you're not spotted because they know the map, where you are likely to find concealment, and of course they can see your shots, if not you.Even when in the best possible position it is wise to have an exit strategy.