How do you retrofit attic baffles in attics with very little room?
Two obvious but invasive ways are to:


Take up the roof sheeting and work the baffles from above the rafters.
Remove the ceiling drywall under the baffle area and install the baffles from below. 


With a low sloped roof trying to work within the confines of the attic will be very difficult. If there are protruding roofing nails the tight areas can be dangerous if you bang your head or arms against the nails. And hope that the workers are not claustrophobic.

I have a roof pitch of 5//12 over my garage attic and I can say even at that slope it is very difficult (but still possible) to squirm down into the spaces to work at the outer wall area. With a pitch of 3//12 I think I would be contemplating one of the invasive measures above. If the roof is shot and needs replacing use #1 else go with the ceiling removal as in #2.