the rar bar on big red was fabbed up from exhaust tubing so not much weight...
I strongly suggest you look into making one up yourself if you want to get the weight savings...
If you dont mind a redesign and repositioning the spare wheel a bit I think it can probabley be gotten down to 5-6Kg for a swingaway.
But Have a think about how you're going to make the swingaway because with a little effort you can make on carry a fair bit more than just the tyre.
I usually like to squeeze at least a small air tank in the wasted space behind the wheel, a mount for a floodlight pole, hook up points for a swag. Go really advanced and you can get a table frame, gas bottle mount, jack + base plate mount, highlift and shovel mount all in one place. And its still not too much of a PITA to get the wheel off.

