Well Neil, I haven't tackled your specific situation, so this is just my opinion. I'd cut the frame rails midway through the outriggers (the green line in the diagram). That might give the best support from the crucifix, plus the outrigger would give support also (see the blue blobs for the welded areas). As for rear frame pieces, I didn't see any in the Kilmartin catalog. If your interested in originality, the toughest part is the seam that runs along the bottom. For the prices I see, I'd make my own rail and not worry about the seam.