I have the Behr in combo with stock system on 90 Syncro Westy.  No second
condensde.  Temps in the front center vent was not as low as I would have
liked...58-60 degrees.. but damed welcome when outside temps are 90+.

Maybe a second condenser would lower those vent temps.

The Behr is old technology...but with the two squirrel cage vans...moves a
lot of air...

My only nagging issue with it is the loss of the radio slot for the center
vent.....the "factory" Behr kit radio box that goes down in front of the
heater cover doesn't work for me...to hard to see....still looking for a
good solution to mount the radio on top of the dashboard.

Regarding air distribution from the rear.....you didn't say what year van
you have...but the "plenum" in front of the outlet ducts in the back
cabinet is an air flow killer.   I had mine off one time and the air flow
straight out of the fans was significantly greater...and a friend of mine
who converted a passenger van into a County Homes pop-top and just cut the
center tunnel at the edge of the roof opening.   He has so much air blowing
to the front ...he doesn't need front air.

DO ditch the plenum in the late model vans would make a big
improvement...have to find a new facing for the front of the cabinet to
hide the grove cut into it for the rear edge of the plenum... and some
outlet vent/vane thing.