Another way with wps i found is to have external gunners (those not grouped with the jeeps). Then set the vehicles on careless, and just up the speedMode when they are hit using EHs, while the external gunners are setCombatMode "red" to just pound away at the bloody milita.
That's how i've done it, and it works very well. Sometimes it messes up a bit, but thats normal in OFP. Never get the same results 100% of the time, or even 50%!