As it was mentioned application of ethanol is now in contradiction with FRA and common sense as well, I would suggest you to use a conventional air dryer or more efficient, state of art and also cheaper plasma filters as long term solution, because there will be no chance of freezing when air RH is around 30% (less than 5% with plasma filters) but for interim following is prescribed:
1. Be sure spitters are working properly and loco drivers drain manually water content of air reservoirs before any dispatch. (Self actuating ones or constant time ones (activated by EBT) are far better than those activated by CCS.)
2. Relocate head light resistors in brake rack compartment and insulate the compartment carefully.
3. Application of cheap (200$ to 700$ each) general propose centrifugal filters to drain water content of air will be helpful.
With introduction of voodoo plasma filters, will be available in Europe market next June, there will be a revolution in air treatment industry. (They are service free and much cheaper than two columns regenerative dryers with the same capacity. I think conventional dryers will be extinct if the claims about plasma filter were true! )
I have a hard copy of voodoo catalogue in German, I didn't find any english reference on the internet! so far . I will add the link if I find it.