I have used Power Service White Bottle successfully for decades; started using it back in 1986 with my first diesel car (Tempo). I have used it my my tractors for years. I have had no issues with it down to -17F in my Dmax and my Kubota. I suspect it's NOT a problem with the additive IF the fuel is a proper winter blend. However, if the fuel is not properly blended, it may ultimately affect the ability of the additive to do it's job. When it was -17F a few years ago here (real temp, not windchill), not only did my Dmax (common rail) and Kubota (mech injection) both start, but they did so with no hesitations or stumbles, and after a gentle warm up for a few minutes, drove away just fine with no fuel issues. So if your fuel is a proper winter blend, and you've added the right amount of PS WB, then I cannot expect it's the additive. But if the fuel is NOT the right blend, it's cause for concern.
Regarding the red bottle 911 from Power Service, I don't think it would hurt, but I'd call them and ask. And specifically, I believe 911 is essentially a product to give relief of fuel that is frozen due to moisture being in the fuel; the alcohol relieves the frozen water crystals. But, if the fuel is not blended correctly for a winter application, I'm not sure that the 911 will address this. I am not 100% sure of this; that's why I suggest calling them and asking prior to adding it. But it seems to me I had this conversation with them several years ago; I had called them with a question about their biocide and got into a side topic conversation about the 911 product. They have a very helpful tech-line group; or at least they did a while back. When reviewing their website info for the 911 product, it clearly states that it's safe to use and will not void OEM warranties if used as directed. Ford has a statement to not use alcohol based products. So there's a bit of a disconnect between them. I would defer to the PowerSerivce folks for detailed info. The PS 911 product states it will re-liquefy gelled fuel, but it also states it will not prevent fuel from gelling. Not sure why there's a distinction there.
From Ford's perspective, you might even call your Ford dealer and ask them what to use; maybe they have a recommended product? "Alcohol", as we know, is a very large and broad term. There are many different kinds of alcohol. Perhaps the Ford statement is just a catch-all warning because going into the weeds in an owner's manual would be too much to digest, and given their nearly schizophrenic approach to additives and lubes .....( ala don't use CK-4, but you can use anything on our approved list, which includes a bunch of CK-4 lubes )... I am not sure they'd be able to give you a detailed answer anyway. MAYBE there are products that use alcohol that are much less harmful, or OK to use only in extreme circumstances. And this is why I'd defer to the PS folks and shy away from Ford's advice, as they have a habit of throwing out blanket statements and then not only violating their own advice, but being mum as to why/how they make these decisions in the first place.
i would call PS and speak to them again, giving them all the details and concerns, and ask about what product(s) to use.
The other things to mention are checking the install of the filters from the recent changes.
Also try to get some fuel from a high-volume source that has winter blends; as suggested from others maybe a truck stop that's not too far away?