My solution for the rear view vs. air conditioning problem is to mount another
rear view mirror on the windshield, inside the bus of course, about three or
four inches above the dash. I got the mirror from FLAPS with a day/night
switch and I'll bet it coat about $10 or less. I glued it to the windsheild
and it works great. I can see as far back as....., well, you know,  I can see
straight back for a long way.

I suppose if there were people in the back seat their heads might block my
rearward view. But if you've got good looking family and friends the mirror
will still be a plus.

Incidentally, I also use a fresnel lens to avoid the nephews and their bikes
and such when backing up. And the truth is "my" rear view mirror idea was
actually suggested to me by a list member a couple of years ago.

My 2 cents
Jeff
83.5 Westy
NYC