I marked the outline of the gear fairings on the bottom skin. Inside I marked the structural extrusions. Then I located holes where the brake lines could exit inside the fairings.
Here is our vent line mocked up, and my fuel catch mockup.
When the catch is in place the vent is hidden.
I have some soft 3/16" aluminum tube I am thinking of using for the drain. I am going to run it inside through the filler box, into the cabin, and out the floor. I am thinking this should be sufficient, though I see others have used 1/4" tube. Thoughts?