My home has a microwave over the cooktop in the kitchen. It doesn't vent
to the outside, but recirculates back to the kitchen. The microwave has a
configurable venting, including top vent and back vent, so I wanted to switch
it to vent to the outside. The problem is, there is a exterior-wall stud
right smack in the middle of the microwave's mounting location, making rear
vent to outside impossible (I think). I can't route a duct directly from the
outside to the microwave vent. There is not enough room above to route
a top-vent around the studs to the outside.

What I can't seem to find out is, do all microwaves with hood venting
capability locate the vent in the center of the back face? Or do some of
them place them off-center to one side or another? Retail stores
"mount" the microwaves in a way that makes seeing the back or top all-but
impossible, and this is not data that I see listed generally online. Anyone
here ever look into this? Any guidance?