It's perfectly possible to use a combination of triggers and waypoints to get the loons out of the jeep and behaving how you want. (And, as always in ofp, there are various ways to do it - you could use a script if you want.) But as Trapper says, the tank will almost always detect the jeep first so it's all likely to be academic.
Have a think about this ... what do you really want to happen? Do you really want a tank there?
Assign the loons to the jeep and put them in it.
Trigger1:-
East detected by West, repeatedly
On Activation: units grp1 orderGetIn false
On Deactivation: units grp1 orderGetIn true
Loop:- (either in script or waypoint)
Trigger1 setPos getPos leader grp1
[grp1, 2] setWPPos getPos leader grp1 (Seek & Destroy)
[grp1, 3] setWPPos getPos leader grp1 (Cycle)
Not guaranteed, that's just a sketch. You'll need a couple of switch triggers synchroed to waypoints if you want this to be able to happen more than once.