RE: Storage with top bunk out
The space up there is 5 1/2" high, just right to partition with
6"x1/2" finished lumber (actually 5 1/2" wide).  I store tarps, solar
shower, small tools, books, video, sandals, a box with misc. hardware
and wire and electrical connectors, shower pump and hose, maps and
tour books for areas I'm not in but travel to on occasion, etc. 
Mostly stuff that I only pull out when parked with the top up.  The
forward compartment (12" deep with fold down door in front) is
reserved for things I know I might need without popping the top, the
small tools I mentioned, the books, sandals, flashlights, etc.
The partitions are about six inches in from the edges along the side,
about ten inches from the back.  My camera tripod in a soft case goes
on one side and can be extracted with the top down, a walking stick on
the other.  Umbrella also.  With the top up the wooden partitions act
as a base for placing larger heavy things up there without crushing
the permanent contents.  It's worked very well and much better than
the two long plastic storage bins I was using before.  I've seen other
Westy owners with similar setups, store clothes, food, anything you
want.
BTW, I believe that the total for all lumber and parts (hinge,
latches) was under $20