For me it is matter of weight distribution.  The left side
of the Westy is already heavy (water/all cabinets/ propane
etc.) so I try to put as much weight as I can on the right
side of the van.  I put bottled drinking water on the right
side under the rear seat, I put boxed juice in the box
behind the passenger's seat.  I put extra water (when
needed) on the right of the exterior luggage rack (up front)
with my tool kit next to that.  Also on the luggage rack I
put items that I infrequently use.

The only weight that I put on the left is caned goods that
go in the 2 top loading cabinets under the rear table.
Suitcases in back, kitchen items under the sink. bedding in
the "hanging closet".  Small kitchen items or frequently
used items like flashlights in the trough above the
kitchen.   In the over the bed cabinet we keep books and
papers (related to travel mostly).  The rear left cabinet
has mostly van fix-it stuff (oil, coolant, books, tools,
extra this-that-& tuther).  We store stuff up behind the
front of the top folded bed, we save this space for stuff
that we want to keep in good condition if they fit up
there.

Hope that helps.  Malcolm