Thule Tracks on a Camper Shell

Hey everyone. I’m curious what the distance between your load bars are on your camper shell. I just got the 54” tracks from Thule, and I’m going to be installing them tomorrow ideally. I would like to space them as far apart as possible to help distribute weight down into the bed sides, but I’m having trouble deciding how to space them.
2 options here, either you have factory rails and you can share what the spacing is from the factory, or you could share with me what YOU did when installing these tracks.

Just as a bit of background, I have a 2008 DCSB and there will be a RTT on top eventually once I finish fabricating an internal steel support frame to make sure the camper isn’t taking the brunt of the weight. Please don’t try to convince me of another route as this really is what will work best for me. I understand that it’s a more difficult solution but this is what I want lol