I know its not what you are looking for, but the Retrofit Offroad front fender mounts work great with Rotopax cans and doesnt add weight the the *** end off the Jeep, just an option. You wont get 10 gallons with a pair of 3.5g Rotopax, but thats half a tank on a JK. With the Retrofit Jerry can mounts you can run 2 5g cans and keep the weight off the *** end.
The Rotopax and mounts can be gotten for off Amazon Prime with free shipping. The 5g jerry can option might be cheaper, I havent looked.
This is over your budget but for me Ild rather keep the weight evened up overall.
Plus I already have a bunch of stuff on the *** and 5g of water, and with a full cooler on the rack I can feel it back there. I carry the spare tire/s inside.