Is it better to keep diesel fuel tank full to reduce condensation, or run it to near empty and add an additive to help remove moisture from fuel. I’ve heard people recommend each of these practices, but never heard anyone compare the two. Which is a better practice?
Just fill back up at 1/4 mark and relax . With storms and other weather events it is always a good idea to have enough fuel to go some place if the power goes off . Running to near empty is never a good idea period. I doubt if condensation is a major problem .
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Air has moisture in it, the more air in the tank, the more condensation you’ll get.
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I think you are worrying about something that may not be a problem . Just refill at 1/2 mark or 1/4 . As for additives I would not do that as it might cause warranty problems .
My opinion, keep it full as possible.
In the states, the parts of the country that have gelling problems in the winter will start selling winter blend diesel, no need to add any additives.
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Keep the tank full. Keeps out moisture without additives, diesel fuel doesn’t go “bad” as quickly as gosoline so there is no downside to keeping your tank full.
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you’re coming across as very aggressive here, for not a lot of good reason. nobody is saying that condensation in the tank doesn’t happen; what is being said is that the marginal impact of letting a tank occasionally get down to empty vs. religiously keeping it topped up is negligible.
I would argue that other aspects of more frequent fueling - more trips to the gas station (time lost), engine stop/start, etc. - would outweigh the benefits that you would see from a small amount of condensation reduction
Keep it full in my humble opinion. No air, no moisture. Simple.
But I would be as concerned about the stuff that grows in the tank too. I don’t know if it grows better in air or not, but grow it does. I think I had 20K on my diesel when I finally had to drop the tank and flush it due to a bad tank of fuel. All kinds of stuff growing in the tank. Maybe I got in with the bad tankful, I don’t know, but keeping it full can’t hurt and less likely to plug the filters that way. Wear a mask if you dump the tank. 
If there were a problem with allowing the diesel fuel level to get low, Ford would have included a warning in the owners manual, and a warning near the fuel level gauge.
Tester
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In the winter in Minnesota, the station I usually went to would do a winter mix of 50-50. They wouldn’t run straight #1. The guy was pretty knowledgeable and said straight #1 was too hard on the injector system. In the winter I would always use an anti-gel additive and never had a problem with the mix. When it’s -20 and some miles from home and the car starts coughing, you use an additive after that.
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Untreated diesel fuel will gel at about -25F, Freight companies in the North always bough treated fuel rather than messing with additives. I used to run to Watertown NY and Montreal via Watertown NY and you could tell when it had dropped to -25F when you would see Southern owner operators coasting to the shoulder because they always bought the cheapest fuel, usually at the Indian stations in NY State. I know the PC term is Native American, but I grew up on a reservation and I never heard anyone refer to themselves as Native American.
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You just reminded me of the mean chili the husband of a girl at work would make. He was a great cook from the Reservation. I’m old enough to remember the Indian Transport Co. Seemed like they hauled mainly tankers at least out of St. Paul.
I worked in a truck shop for 40 years. When it got colder we always kept the tanks full. Tanks were aluminum and got a lot of condensation
This may not be relevant now, but a friend of mine had a diesel Econo van late 80 model. He ran out of fuel once and it cost him about $100 to get the fuel filters bled. So you may want to avoid that happening. Diesel technology has improved a lot since then so it may no longer apply.
On mine anyway, the trick was to open the connection on the filter a little to bleed the air out. Otherwise crank crank crank on a $300 starter.
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We always used Starting fluid to get a diesel truck engine started after it ran out of fuel but big rig engines are pretty tough, not sure how a light duty diesel would take that.
To prime a diesel engine when replacing a fuel filter we would fill the new filter with ATF. With common rail diesel engines, after replacing the fuel filter, just tap the starter, the lift pump will run for 30 seconds filling the new filter, then start the engine.