In article ,
Mxsmanic wrote:

I was thinking of stuff that's always there--maybe a first-aid kit, or
some basic survival gear, extra water, oxygen, or whatever you
consider necessary to make you feel warm and fuzzy when flying.

This isn't your room where you keep your computer when simming.
Go to the manufacturers websites and lookup the cockpit dimensions.
find some large pieces of cardboard and cut to size. Tape the cardboard
together with duct tape.
Now you can see how big the volume is and determine for yourself what
you can and cannot carry.
You cannot include the toilet in your bathroom nor the refridgerator in
your kitchen.