Wow, so much useful information from a multitude of angles - thanks everyone.
Weight is a minor concern of mine since this is a RAM 3500 with 4k payload and the majority of the roads I have experienced over the past several years are maintained trails with some unmaintained ones. Since the early 90s I have been building and wheeling Jeeps on some pretty extreme trails so my focus now has been more on back country exploration versus let's see if I can make it over that obstacle. All that being said weight is still a concern so I am not reckless regarding piling on pounds.
Regarding temporary and permanent solutions - when I envision a temporary solution I see two Jerry cans for diesel and four for water which is fine but I am not really keen on storing diesel inside the FWC. Many I have talked to say it is a non-issue but I have no first hand experience so by default, my desire is to store the diesel externally.
If I am going to store the diesel externally this is easiest accomplished with the thirty gallon tank under the bed - problem solved. Now that leaves me with two additional slots internally for water so six Jerry cans instead of four. And yes, I can keep weight down and leave several of the empty - same with the diesel storage under the bed.
Another person shared an idea of relating the storage capacity to the range of the vehicle although my plan is to spend at least two or three days in a particular area, move a bit, spend a few more, etc. I believe my goal is to spend 10-15 days out in the forest or mountains until I stop back into town to refresh, resupply, etc. Then again, these are just plans and ideas for me at this point.
I guess ten gallons of diesel and twenty gallons of water inside would be a good place to begin - I am just concerned with the smell of diesel.
Does anyone have experience or knowledge related to the SCEPTER or WAVIAN five gallon fuel cans?