Hi Larry. That one has always confused me too. You go to all the effort to drill some holes, that appear now to be essentially useless. Fortunately I got the thumbs up from Van's to drill another series of 5/8" holes about 7/8" from the floor and about 1 1/4" forward of the seat pan lip (or just aft of the stiffening bulge in the rib). It appears that even this isn't quite right as it conflicts slightly with the position of the roll trim servo, so it looks like I will have to drill a new access hole on the most onboard rib. Hindsight can be so cruel sometimes. Still interested though in how to get around the control column mounts. I am thinking a bit of flexible conduit that firmly fits these 5/8" holes, with sikaflex in both ends to doubly make sure it doesn't move. Start it at the rib just outboard of the control column mount, run it around the mount and into the hole on the rib on the inboard side. There appears to be room at all control angles for the conduit. Have the conduit under a slight bit of tension to stop vibrations and place another small dab of sikaflex between the conduit and the control column mount to further stop the chance of vibration.
Tom.