We have a few simple rules in our house.
1.Everything in the trailer must have at least 2 uses
2.If the trailer needs it take it from the house and buy another one at the store later.
3.If you don't have it when your out ask your self a simple question will you live with out it, if so wait, if not then go to the store and buy it, dummy.
4.Nothing leaves the trailer.
5.Sheets, Towels, and clothing are not subject to rule 4.
6.Trailer can not go back to storage (leave driveway) until sheets and towels are washed and back in trailer. This one only works because it blocks almost the whole driveway entrance.
Those rules coupled with the fact that we started with just a truck and tent and moved to small (18') RV then to Pop up (10') and mini van made sure all the essentials have a very small foot print.
All my friends wonder how I have all this stuff and it all fits in about 1/2 the space they have