Haha thanks/no worries. On the PE, you attach the rails to the canister as the first step, sliding them onto the canister (so the canister has to be positioned first). May be different on the retrax. See 5:09 in this video.
I see! If you have the patience, I would do the following:
1. Place a couple of indicator marks over each rail and your bedrail so that you can reference later.
2. Disassemble the rails from the canist and remove.
3. Install rambar with only a cpl of bolts, loosely fitted, just to ensure it's in the correct position.
4. Place your rails over your bedrails and the rambar (without canister) referencing your previous marks to position the rails where they belong. (Front to back positioning)
5. Mark each of the four radius cuts on your rails, and make your cuts.
6. Remove rambar.
7. Install rails and canister, but keep canister and rails up high off the bedrails. (Per the attached screenshot from the video)
8. Disassemble one side of the rambar. (See attached pic for reference point)
9. With the rambar split into two sections, you can work each section Independently without the narrow clearance. With the canister and rails still up high, that will give you the space necessary to install the rambar bolts.
10. Lower canister with rails onto rambar and bedrail. Radius cuts should align with rambar tubes.
Also, I would apply clear or black silicone around each of the radius cuts.
Make sense?