Ok, here's something, to me as a Interim measure I found a side tank from a Mercedes 508 truck, I think I install that on the pass.side, and have the fuel transferred with a electric fuel pump in the oem tanks.
Then, when I'm allowed to drive the truck and summer is coming I'll concentrate more on finding a sulution to fill the oem tanks from the fillers.
Thanks for the ideas, and I ask still, if someone has a new idea of which i didn't think of yet, please propose it here in this post, to me this is still a temporary measure.
Thanks, Bart
PS where I live US trucks are rare as hens teeth, and most of the parts have to be shipped from the US over the big pond.