Rays Outdoors might have the solution for you. I can't see it on their web site, but I saw it in store - has an attachment that looks like a fuel bowser outlet. I might go in store after work today (if I get the time) and take a look for you.
Problem is, any solution like that will require that you can get to the jerry can to undo the lid and attach the pump. I've thought about this myself, and decided that rearranging the tub so that my extra fuel is carried near the tail gate is the way to do it, so my fridge sits near the front with access from the passenger side. Tools are in between that and the battery box over the driver's side wheel well, jerry cans sit immediately behind the toolbox with the generator and its fuel sitting to the rear of the aux battery up against the wall near the tail light.
If you replace your rear bumper with a bar and add jerry can holders, I think it's illegal to store any fuel hanging off the back of the vehicle. I was considering getting some jerry can holders for my caravan and storing 80L of diesel on the back, but was told it contravened the laws in relation to the carriage of flammable liquids. That would have been a neat solution giving easy access and keeping the fuel away from clothes & fridge, but such is the way of some bright ideas.