Yes, Luke at
www.fourtreks.com has a product that would work.
It works with the 1.75" rings to mount on the stock rack.
I bought the part from him, but I have not gone out and bought a jerrycan holder again yet.
I gave my last one away with my Yakima rack from the old rig.
I do not have a picture of the item, but it is a bar that can sit vertical or horizontally depending on how you mount it.
The bar has some bolts with it, and you could run them through the back of one of those shorty red jerrycan holders.
Lemme see if Luke has the item up on his website.
Standby please
Found it, it is the fire extinguisher mount.
http://fourtreks.com/modular_fire_extinguisher_mount.html
Mine is on my PC table as I type.
You could get away with one of these I bet, as the maximum width of the holes is about 6", that should hold a mount like the one I had before.
That mount below will hold a 2.5 or 5 gallon jerrycan.
I ran the smaller sized can.