Actually, suppressive fire is EXACTLY part of the use of the lafette. They were specially issued with heavier barrels for longer sustained fire, and, when doing suppressive, were meant to be a hold the trigger down kind of weapon.
http://www.youtube.com/watch?v=2vM7vV686Tc&feature=relatedGo to 2:58. Its hard to find true combat footage of mgs, much less lafette, but that is actual footage from the fj drops in holland. There's another shot of that same crew, longer this time, at 3:20
Belts were used with lafette, the drum physically cannot be fitted on it.
It was accurate to 3500 yards, and from testing ingame with observers, it is right on ingame, you can hit targets 4 grids away accuratly. Beyond that, I bet u can, but game limitations and such prevent you from seeing it. The sight is also correct, a simple pyramid crosshair. Range adjustment with it was done by preset degrees written on the degree plate on the tripod, and with the observer every gun crew had.
So basically, the things that need to be tweaked are:
Ammo capacity to 250 round belt
Less overheat
Now, far as I have heard, the MG42 version at least will be the 250 round belt.