I've been away for a few days and just saw this discussion.  I fashioned a
cure that causes me to turn UP the thermostat on 95-100 degree days and looks
pretty decent.  I used 3" PVC pipe to duct air from the two outside A/C vents
to a modified early bus interior roof air distribution box mounted on the
roof between the front seats.  I moulded transition pieces for the vent to
pipe and pipe to box connections out of bondo, using cardboard as my molding
dies..  The pipes snake against the  side walls until they're over the front
seat area,  then they go to the center to connect to the distribution box.
 There's little inconvience to the pop-top utilization.  The box I used has 4
vents -- one out each side, one pointing down, and one at the front of the
box blowing in the backward direction.  All of the above was painted gray
matching my '87's camper area.

Let that sun be shining in on ya!  You'll be COOL!