I think they should grab shields from the prison riot gear, set up like Roman Centurians with improvised pikes and short swords, and periodically clear zombies from around the fence.
Also get some contruction equipment and build some earthworks for the zombies to fall into.
Zombie traps, too, to thin numbers.
Heck digging holes with a post hole digger with pointy sticks pushed down from the top in Comanche-style foot traps would work well. Zombie steps in and gets stuck.
But that’s just me.