These are things I have found that are very useful living in a camper. I use these myself.
This is definitely a must have in winter months!
Camco 25 ft. Taste Pure Heated RV Drinking Hose 22911
When space is limited this is a definite space saver!
Tindbea Toilet Paper Holder with Phone Shelf
When you don't want to put nails in your rv walls put you want to decorate.
Adhesive - Hooks - The Home Depot
I have found adding shelves inside cabinets helps alot!
Space Saver Shelves
In the cold winter months this helps insulate the windows and keep out the cold. In the summer it reflects the sun and keeps out the heat. A definite must have!
Reflectix, Inc.
These are nice when it's time to put away all the winter items. Then use to put away summer items as well.
Spacesaver Vacuum Storage Bags 15-Pack
If you live in your camper where it gets cold in the winter like I do you will need something like this.
Best Electric Mattress Pads
This is also must have. Other wise you get a smelly camper.
I really recommend a space heater. It keeps your furnace from running constantly to keep your rv warm. The radiator type especially is nice. It doesn't just push heat forward. It has heat coming out all around it.
Radiant Heaters - The Home Depot
These are crucial for keeping the warmth in and the cold out in the winter.
Vent Covers For Rvs
I have the pink stuff under my camper and it really helps. It keeps my pipes from freezing as well as my water pump.
Rv Insulation For Winter
You want this also. These can also keep the cold out. Rv doors aren't sealed very well.