Do you really think the non-farm driving public is going to see flashing/rotating beacon lights, and know what they are there for?   In my opinion, there are way too many vehicles with flashing lights/rotating beacons.  They have become meaningless. 

Emergency vehicles - and only emergency vehicles - should have flashing lights. Any more than that just defeats the point of having them.

Farm vehicles should have SMV signs.  That is all.

In my opinion.