I'll be working on my own swing away tire carrier this spring. I just ordered some oil impreganted bronze bushings and a bag of zerk fittings from McMaster Carr. The bumper face will be 2x6" rectangular tube 3/16" wall, with either 2x3" C channel or rectangular tube for the attachment. Other bumper basics will include an integrated 2" receiver tube (hitch pin behind) and "K" braces from the rear of the receiver to the frame.
The swing arm itself will be 2x3 tube, with a triangular brace to the vertical post (prob 2x2" square) and adjustment via 2x2" tube in another receiver with locking hitch pin. There will be a vertical hi-lift jack holder and possibly accoutrements for a single jerry can (Sceptre type, plastic). As stated above, I'll be using bronze bushings with a steel (I believe it is mandrel tube that has no seam) sleeve and a 1" grade 8 bolt. I may try to slide in a delrin washer or two as well, though I think it will be overkill. It will definetly have a zerk fitting, and I may machine a lazy corkscrew pattern into the bushings for grease on the lathe.
I haven't decided on the type of latch system yet, though I'm leaning towards simple and spring loaded. I also have a few ideas for a pin that would hold the arm open and out of the way. Lastly, I will be looking into doing some sheet metal trimming underneath the plastic corner pieces, and re-locating or -routing the cabin vent. Side protection tied into the frame would be a neat job, though I'm thinking it won't be feasible for this go around.
Below is my first attempt at a rear bumper. We'll see how the next iteration works. The current bump has been working out very well, and I learned alot during construction. It currently has a better paint job (Hammerite) and much nicer grip tape (sweet 3M type, matches the grey paint).