I did the same thing my first year with the district. One school had a room
,the other was a cart.
When we painted, I carried one large bucket with clean water and another
empty one to dump the dirty water. I also put the brushes in there to soak.
I have a drying rack which I would roll and station outside the grade level
that would be painting before classes started. It was there when I needed it.
As far as rules, I posted them on the side of my cart. You can also get a
small table easel for dispaly. I always brought something to write on as
there was never any board or overhead space for me to use. A large pad of
white tear off paper was a great help.
This year, I'm full time at one school and I've had my own room for four
years. Working from a cart is do able. You just have to VERY organized. I
had a tote tray for every grade level that contained the supplies just for
Good Luck! Janet