Hi Mohoender!
Well, I really have also zero experience with wagons and the like save for a few sightings during a few infrequent visits to the provinces. I've seen a lot of water buffalo here though and they seem rather strong from what i've seen.
Those are respectable qualities you stated there with just 2 horses pulling the wagon.
The tachankas i envision in my game may also take the form of cut-up and lightened car/van/light truck chassis rigged to a horse yoke. I've seen some of these in our rural areas here and they seem to work.
Your suggestion on multiple LMGs did get me thinking. I agree. I spotted a picture while googling this point on the net and came up with an early german WW2 set up with double MG34s mounted on a horse-drawn wagon. I can imagine the firepower this can bring to bear against two-legged targets of the player character variety.
