We did this very thing on the VS for our -10 (
mod to top rib). We only had to drill a hole through the top rib since we passed the conduit through the lightening holes in the other two ribs. We used proseal to secure it at various places to the ribs and the front spar (
pic on this page). I asked Van's prior to doing it and their response was "we've never thought of doing that, but don't see why there should be anything wrong with it". Based on the flying RV's I've seen with wire runs through the VS, and the fact that Van's didn't see any problem with it, I felt pretty comfortable with it. YMMV.