The OE spare tire carrier is barely adequate for the spare tire, it's not even close to being able to support the weight of two full 5-gallon jerry cans and steel support pieces which would add at least 70-75 lbs. of additional weight.
Some aftermarket spare tire carriers are strong enough to carry two full jerry cans, take a look at what OR-Fab | Off-Road Fabricators | HOME
has. I had their jerry-can version spare tire carrier on my previous TJ and it was superb at carrying both a large spare and two full jerry cans.