My two cents:
--If you will be alone the headroom should be fine.
--Wet bath (Shower stall with porta-potti to save room and money, and for simplicity. Hanging solar shower or garden pump sprayer shower with water heated by sun or stove. Shower curtain instead of walls makes cabin seem roomier when the curtain is retracted or removed.
--Small bar sink with foot pump faucet in galley only. Pressure water systems are overly complex and use more water than manual pump. A foot pump makes washing hands much easier.
--Simple solar power system for all house electrical needs. Try to keep everything 12 volts, with maybe a small PSW inverter for your computer. Avoid need for generator.
--One burner, or maximum two burner propane or butane tabletop stove. Portability saves countertop space and allows for cooking outside in nice weather. Baking can be done with a dutch oven and charcoal (outside only).
--Skip the loft bed and opt for a 5' long couch that can double as bed, or dinette that can convert to bed. Dual use is your friend in small spaces.
--Weight distribution: Keep added weight to a minimum, and center of gravity low and centered. This will affect driving performance/handling/fuel economy. For example, if you have your water tank on one side, mount your battery bank on the other side. Depending on your vehicle and your ability to customize, you might even mount these two heavy items UNDER the floor.
--House A/C is a big space and power hog. Park in the shade instead.
Disclaimer: These are just my opinions and are worth exactly what you paid for them.