Different strokes for different folks. To this point I think that suggested steps are something all trailer owners would benefit from, but from this step forward, you may want to do something a little different to fit your specific application. Food for thought.
I choose to put 3/4-inch plywood up the entire wall because I wanted to give the trailer enough rigidity to allow heavy items to be hung up. Choose to go with lesser material and you might end up disappointed when you try to hang an ice auger or spare tire on the wall.
When purchasing plywood consider getting a type that has a least one side with a quality finished grade. I chose untreated plywood because I planned to finish it with another product, which we will talk about later. An exterior, or marine-grade plywood is an option, but more expensive. Simply painting it will keep the moisture out if that is a foreseen issue.
Attaching the boards to aluminum studs requires a unique type of fastener that is not likely available at your local hardware store, if it is, perhaps not in the quantities or price you will like. Plan on at least one screw every linear foot.
You need a self-tapping screw that can be used in and hold plywood, but also one that can be used with metal. Flimsy screws just won’t work here. Pay for quality!
Pre-drilling pilot holes and using a countersinking bit in the plywood allowed me to achieve a solid flush finish without wrecking the screw threads. Consider using a chalk line and marking out each hole to pre-drill before you attempt to hang it. This will make it much easier to get a square without throwing your back out.
In addition to the screws I choose to use a sub-floor adhesive on all parts that will be making contact, including the plywood edges that butted up against each other. This type of adhesive is available in large tubes and relatively inexpensive.Adhesive on edge
When placing and securing the first piece take your time to make sure that it is square so that each subsequent piece fits also. For this reason I used full sheets of plywood with factory edges on each side and just cut the top off to fit the height of the trailer.
Capt. Ross Robertson