I have no experience with these pickups, but I do have experience with big trucks. The fuel filter is generally the first to gel. If you have extra filters you can put on a warm filter with a 50/50 mix of Diesel and the white bottle of Power Service. You need to dose the tank with Power Service also. I would go a little heavy with the directions on the bottle.
This.
Whether you use Power Service (I do, silver in summer for cetane boost/lubricity, white in winter for anti-gel), or some other brand or even kerosene. (You call it "Diesel 1": everyone else calls it "Kerosene".

Same stuff.)
With the fuel rail, the injectors are oversupplied and the excess fuel gets dumped back in the tank. That's good. It'll add a little heat, it'll mix ingredients, and it will stir up the fuel.
When gelling occurs, you've got to add a lot of "your fluid of choice" right to the fuel filter. Just take the lid off. Pull the filter: if it's covered in gelled fuel, just wipe off. In fact, if you can, pull out any gelled fuel in the filter canister. Replace filter, fill to the top with your fluid. Add same fluid (Power Service or Kerosene or whatever) to the fuel tank. Power Service also sells a "911" de-gel fluid. If you're gelled, I'd use that.
Your goal will be to get the de-/anti-gel additive to mix with the existing fuel. The fuel line from tank up to filter will be the biggest obstacle.
Let it sit for several minutes (or, overnight if you have the time). Try to start.
Your best friend will be heating a garage.
Specifics of how much to add will depend on what you use. Read the instructions and don't be afraid of being a little heavy if you've already gelled.
Edited to add: if you do add Kerosene, don't go past 50:50 fuel:kerosene.