30 Watt thin-lite florescent fixture over his dinette table:
Removed the shower head and replaced it with a normal sink sprayhead, now it will not drip while you soap up. For some reason the shower heads always let water out to maintain the hot/cold mix while taking a shower. I have found that this is not needed for an RV shower ,plus it saved on water, a plus if you are not hooked up to water.
A handle on the screen door to be able to close it without breaking the plastic slide tray when used to normally close it.
A screen door lock, we like to have the screen door open for more air but the idea of it being un-locked made my wife nervous so I installed a lock
I like a lot of Darios's ideas. I used a kitchen sprayer as a shower head in my Roadtrek and it worked well. Saves a lot of water when dry camping!