To update, I decided to go with a 68 gallon (267 l) in-bed tank, along with the following system by ATTA :
https://www.attatank.com/freedom-fil...y-system-info/
It wasn't cheap ( I had a local dealer do the install as well) and will likely never pay for itself in cost savings, but as far as piece of mind, it's priceless to me.
Even the DW, (who was strongly against the idea because of cost) is now a firm believer
I have been on 2 longer trips with it, and so far I am very happy with how it works and the whole "fuel stress factor" has been a non issue on both trips.
I can now easily get 600 miles on a load of fuel, which is about 200 more than I am comfortable with in a day, and that is exactly what I was looking for.
Thanks to all who contributed to this thread and helped me "think" it through.
Appreciate ya!