I doubt this rig ever sees a campground with specific sites - it will be going to recreation areas where it gets parked in any suitable location, probably in a desert.
The vehicle deck on the back looks problematic for weight distribution, but it probably runs a reasonable pin weight fraction with the FJ Cruiser on and just extra-pin-heavy otherwise... and only hits the highway with the FJ anyway. Personally, I think it's likely a much better idea than putting the FJ on its own trailer behind a fifth-wheel.
The trailer-on-trailer construction is unnecessarily heavy and awkward (it must be quite the staircase into the RV), but it would be structurally sound and would have been quick and easy to put together.