Caravan loot should match the cargo the caravan was transporting. If the loot is bulky, attackers should bring mules and wagons to snatch it and getaway
Atackers would essentially become defenders, albeit labeled as criminals now!
Everybody else should have free rein to dish out some street justice and assault the criminals defending the caravan
Flat bed wagon suggestion for looters and for people carrying cheap stuff in between freeholds or running small errands:
- no armor
- cheapest in the market
- "Warp speed, engage!"

The attackers should be able to successfully loot and haul away the treasure. It's pretty lousy to hand them glints that they'll just stuff in their pockets and nobody will be able to pickpocket or kill them to drop glints
This design also allows the original defenders to transfer the loot from the first wagon into a second one and continue their journey if they are in the same party