RE: Stopping The Sun
Well, not really, it might get a little cold around here.  But for
minimizing interior heating of the van while  parked in direct Sun Jonce is
on the right track. You have to stop the sunlight before it gets into the
van. I used to camp for a full week in one place at high elevation and in
the July Sun. The only thing I found effective was placed on the outside of
all the windows.  I made covers of Reflectix for all the windows.  But the
really big difference I was able to make was when I made a reflective
shield for the pop-top.  Although none of this kept the air inside from
reaching or exceeding the outside air temp the van was not nearly as heated
up going into the night, it would cooled down much faster.  YMMV