So how do you wash your undercarriage in the winter months?
Climate-controlled shop. I guess I`m spoiled but I`ve prioritized having that since I was a young guy.
I put `em up on jacks and stands (not needed with Tahoe) and slide under with a creeper after rinsing the worst off with the undercar wand.
Just as an aside, with most of our vehicles getting a bit elderly I find that the final work under there lends itself to a thorough inspection of the mechanicals. I`ve spotted just *so* many things that were the first indications of needed service, my mechanics have quit bothering to say "good thing you spotted that when you did.." and now they *expect* for me to find looming issues long before they would. If you look at every square inch of the underside and engine compartment regularly even a layman can learn to spot when something`s not right.
I was considering just using the coin op washes in the cold months to rid of the undercarriage salt.
That`d be a lot better than nothing, but *I* would worry about it missing areas that might retain salt. I`m thinking specifically of *your* car...there`s a reason why I will *NEVER* drive the Crown Vic in the salt

Ford`s build-quality ticks me off, but OTOH their vehicles don`t cost what the Audis do either.
The original owner of my `93 Audi ran it through a relatively decent carwash regularly and always got the undercarriage spray. But the brake/fuel lines still rusted out from salt exposure and cost me a fortune to have fabricated. They *must* be carefully cleaned with long-bristle brushes to get all the salt off and doing some of that simply takes a lot of doing.
I`ll be LPSing my undercarriage next month at some point as the car is still brand new and hasn`t seen salt.
You might find that addictive

While you`re under there, look for any places where Ford might not have really painted things in a decent way and take care of those before it sees salt.
I just straight up don`t have that kind of time and devotion lol. Not on the daily.
Understood and perfectly sensible. Part of why I do it is that my wife and I don`t want to replace the current vehicles (we like *exactly* what we have and doubt we could find better examples). For me, overkilling stuff like this is better than buying "disposable cars" like I used to...don`t like today`s stuff and the older vehicles we do like are always pretty trashed. At other points in time we just bought/used/sold the disposables without getting all invested in their upkeep and that aproach *did* have a lot going for it (I still think about just leasing a bottom-rung VW and not being at all Autopian about it).
Do you do the same as me and just spray it down with water? I try and stay away from the soap those places have.
I`ve never used my 1500C`s soap injection, just water.
Just FWIW, I don`t do too many marathon sessions with my steamer, but I would *NOT* want to be without the continuous fill. I`ve had the stop-to-fill types and it was much more of an issue for me than I`d expected. Won`t be that way for everybody, but it turned out to be critical for me.