Love plastic storage containers. Make sure you get the type that has a good locking mechanism. Mine all have handles that bend upward to secure the lid. Less chance of stuff popping off when towing.
My storage compartment is organized with containers for my plumbing accessories and spare parts, another for electrical accessories and spare repair parts, and another for misc. junk like eternabond tape, spare dicor, heat gun, caulk gun, cordless drill, airpump, etc..etc..
I upgraded to clear containers because I kept forgetting what was inside of them. Now a quick peak helps jog my poor memory.
Another thing, make sure they are waterproof and the lids are NOT recessed. Recessed lids or lids that have grooves easily trap rain water. Flat lids give you the option to keep your containers outside under the camper without fear or the lid trapping a lot of water. I made that mistake once with a storage container that I keep my wood pellets and BBQ equipment in at my residence. Recessed lids do allow for stacking containers inside your storage unit but I use Velcro on the top of the lid and bottom of the stacked container to solve the problem of them shifting when I tow.
