How about using something similar to the way the satchel charges and basic mines are simulated?
I mean create a "detonator team" of 1 or 2 guys, size 0, little or no weapons
except for one shot of an "IED" weapon that they will, in effect, "shoot" at the convoy.
This weapon would have to have huge HE effects, enough range for the unit to reach the target, and enough accuracy to hit a moving vehicle reliably enough (not that IEDs hit bullseye every time, of course).
If the "detonator team" (make that the guy overlooking the proper priming of the IED, you have to have someone anyway otherwise you can go for mines just the same) can be positioned just next to the target, then you can make his IED "weapon" from the standard 1000lb bomb that should be present in every OOB (for the ammo trucks death effect).
I'm not very in favor of this kind of solutions (as was advocated for laser-guided PGMs f.e.) but in this case this is the best solution I can think of. If anyone can find a better one...
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