A couple years ago the C&TS built a similar-sized/designed pavilion as a short-trip summer dining/entertainment venue 14-miles from Chama on Cumbres Pass, used mostly by weekly kids trains.
Its identical gable roof trusses went up in a day or two by four workers and a truck crane, was quickly completed.
To raise the Car Barn staging, I'd lay old plywood or planks over the mud, get after it ASAP.

The Alna weather post shows steady, above-freezing temps, 50s and 60s highs for the next week.
Hopefully, Mr. Snow is leaving town rapidly.

Ain't spring great?