You will need some sort of securing system. Home Depot carries Simpson Strong ties (thats what we use) A couple on each side of the two panels and drywall screws would be all you would need to latch them together and you use 2x4's for bracing on the top.
Materials you can't use in my area would be nothing rubber,no tires at all not even on props. If you want to use a car or a riding lawn mower in a schene take the tires and gas tank off.
Black Plastic! Big No No! Has to be convention tafita(SP),water needs to be able to go through. Tafita= expensive, which leads to not covering the top of the walls with plastic or paying through the nose.
You may get away with camo net,we do.
No hay bales! Any cloth needs to be flame retarded!
Do you need emergency light up signage? We have to have one every 120' at an emergency door. Big bucks once youve got the electric line to power it added in.