Rost processing in winter

Hello, I found various rust spots on my 18 year old Octavia at the front above the windshield, safely caused by rockfall. Normally I would clean the areas, rust converters on it + wait + wash off, Brantho Korrux 3in1 on it + dry, paint, finish. Maybe after the rust converter and before Brantho still something with zinc. The result will not be nice, but I think/hope durable and that’s what matters to me. Now to the problem: Mi r is only available an unheated barn which is not very dry at this time of year. What do I do now? Wait until spring and hope that I do not have a hole in the roof until then? Or carry out work with the conditions above and hope that the varnishes/colours also work at the temps. What do you mean? In the appendix a few pictures.