I built this for EJS this year. There's a few things I'd change.
Tire sits WAY high. Can't see a thing and I don't have any side mirrors on with my doors on. That sucks. I do like that it's high so I don't scrub it when coming off ledges and such. I'd like to move the tire down about 6" and see if that makes any changes.
I used a pull-over type latch on the bumper. It rattled a lot more than I wanted so I put a pin in the top near the tailgate latch. Helps with the vibration quite a bit and isn't to bad to undo both latches.
I've heard the criticism of the trailer spindle type carriers in the past. 1) I've heard they break. This is definitely possible if you just used the latch on the bumper. I thought with the vibration that was present, the spindle could work harden, crack and ultimately shear off. This would happen whether the rig was driven to the trails or carried on a trailer. I was quite surprised with the vibration that was present. Some could likely be reduced by remanufacturing the latching area of the bumper/carrier but it just seemed like you'd end up needing two latching mechanisms to secure the swingout to the Jeep. With my Jeep having the cage tied to the frame, I thought I'd be OK with latching to the body. If you've just got a normal setup with body bushings, I'm not sure I'd attach to the body.
2) I've heard they swing to freely.
This is true. I need to install a limiting device of some kind? Current thinking is trying to adapt some kind of hood strut to control the swing and install a stop on the carrier that buts against a stop on the bumper.
Bumper is 2x4 steel (I think 3/16---think super heavy like everything else on my Jeep), a mix of 1.75" DOM and 1.5" pipe and some other scrap steel I had kicking around the garage. Spindle kit is from Summit Machine.