Dead easy. S3D is really perfect for that : you create 2 processes.
In process 1 you enable the external perimeters for the left extruder.
In process 2, you enable the infill for the right extruder.

There are some constraints however, I think the 2 layer heights have to be multiples. You can see the option in the table. of infills. And yes, 0,05 with a 0,8 nozzle will probably not work.

There is a tutorial on their website.