Up until now I've used an Alpkit double ended dry bag (13 L or 20L) strapped directly to the Jones bars on my Genesis. With the arrival of the Cannondale fat bike with lefty fork, I needed an alternative as
a) most harnesses strap to the fork crown and
b) I was worried the lefty fork will make a dry bag sit wonky, although the SQ lab 12 degree bars I fitted help with this, as they sweep slightly forward before they sweep back.
So my solution (hopefully! Time will tell) is to use 2 handdlebar extenders designed for mounting lights etc. £13 each from Amazon, I went for the alloy bar, not carbon, to minimise any impact the straps rubbing.
I just run the 2 dry bag straps around the dry bag and behind the two bar extensions. On a brief test run it feels pretty secure. My bivvy and sleeping bag are 1.6 kg so hopefully between the 4 Individual brackets it'll stay secure. I've angled it to give the best compromise between bag and wheel clearance with suspension compressed, it not sitting to high, and giving the cables and hoses some room.
Ideally the bar part would be slightly wider than the 20cms it comes as, but it's just wide enough to work with the strap guides on the alpkit bag
Some Gorilla tape wound round the ends of the bar extensions keep the straps in place. I've only got pics without the dry bag but I'm sure you'll get the idea....
and much cheaper than £130 for an anything cradle! although i did consider cutting the base off a plastic anything cage and mounting it in front of the 2 bar extensions but it feels pretty secure witout it, and pullnig the straps tight compresses the bag between the 2 bar extentions a litle - helping with stability.
Not so much a gravel grinder.... more a gravel (mud and tarmac) groveller...