4307 that rack is awesome! I especially like the low-profile feature and the holes in the angle and PSP stock allow for infinite tie down options when lashing gear, besides the other features you mentioned. I'm thinking your idea is my solution for a rack over my CanBack. A couple questions though...
* what does it weigh, approximately;
* what specific material did you use;
* how did you secure it to the cross bars;
* what are the small square cut-outs on each corner in the PSP for?
Thanks for sharing your pics and ingenuity!