I made a double tier sling that hung on suction cup hooks under our bathroom sink in our '04 SD for our microfiber towels. Also IKEA has suction cup bins that work well on the walls, and I stored plastic shoe bins on either side of the toilet with TP, shoes, laundry pods, etc. Added an extra towel rack on large pipe in bath. I made storage pouches for both back corners (glasses, flashlight, Kindle, etc.), also one for the carpeted bathroom wall, and either side of the dinette secured with drapery hooks. I also made mesh zipper bags the depth of the back overhead cabinets for clothing storage. We made sure our clothing could be easily rolled (dry fit, etc.) and took layers for trips where weather would range from 30-90 degrees. Rollable space bags for bulky clothing, stored over back bed. Stackable pots for cooking, took out microwave
for storage. Took 3 plates, 3 bowls,2 insulated cups, and a stainless steel bowl that served for mixing/storage. Stored a child size broom behind the fire extinguisher and fly swatter on a hook above that. Closet shelves. Took out large dinette table since bed was permanent, made support from 3/4" plywood which made it easier to store stuff under. Command hooks in kitchen, extra rack on back wall for spices. Oh, and magnetic paper towel holder on end of range hood. Just be creative, and try to make as many items multi-use as possible! Had our Casita for 5 years and several extended trips. After each one we reassessed what we used a lot and took out stuff that we didn't. Cooked mainly outdoors, used a small tackle box for cooking utensils and that stored easily and could stay outdoors. BBQ, camp chairs, screen room in back of Nissan Frontier and suitcase solar
rode on bed. We limited our loading to 250-300 lbs, and it is amazing how that makes you rethink what you pack! There were some trips we had empty storage bins!