We have bought a number of suction cup towel bars for our tiny bathroom, from EZ RV products.com, but right now I can't get a proper page on their website pasted.
They can be used indoors as well as on the outside of the rig when you are parked. Love
We had a carpenter make magazine racks for our interior. Two in the rear by the benches and one behind the driver's seat. Worth every penny for we who are not very handy.
The Container Store is a great resource for organization items for the kitchen, i.e. stacking/locking containers for herbs, seasonings, etc., and packet pockets to hold small items inside the cabinets. Whenever you can use that empty vertical space, it makes a big difference.