They could always cut trap doors in the containers with ladders to allow completely protected transit from built up fighting position/bunker/observation points, possibly with a firing step and loop holes near the ceiling of the container instead of guys with rifles trying to fight from the crenellations castle-style. Then (assuming they had the kit) they'd just need a couple machine gun teams and maybe a couple marksmen with decent optics on their rifles with really good observation/fields of fire topside. (And even the MGs could be protected by gun shields and such -- if the threat has little or no heavy weapons a fixed MG position can be a lot more blatant and static than if you've got to sweat RPGs and mortar fire.)
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