Finally got around to measuring and ordering a bike rack from ISI (
iSi Advanced 4x4 Bicycle Carriers | Extreme Duty | Offroad | Cars | 4x4 | Caravans and Camper Trailers ). Seems awesome. The rack folds down easily, and the swingout still opens even with two bikes on the rack. And the bikes are tucked in close to the truck (the hitch has multiple holes - so I can scoot it in as far as clearance on the inner bike allows). And it's pretty far up in the air.
And even if I did something really unfortunate on a trail - from what I can tell the parts on the rack that would bend are easily replaced. Either that plain square beam that the wheel holders attach to (cheap), or the wheel holders themselves (which don't cost much either).
The hold-down hook is a bit on the crude side - it just has a wingnut that tightens down on the shaft instead of a lever clamp of some sort. But it's simple I guess, and that's the only part of the rack that touches the bikes outside of the tires. Far better than the previuos rack I was using where the rack would grind on the top tubes, the bikes would grinde against each other and to help prevent that I had to spend a long time each load/unload carefully rigging them all up with bungee cords.