SHPO: State Historical Preservation Office(r). These are the people who oversee all restoration and construction activities at historical properties within each state. See
[coloradohistory-oahp.org] New Mexico has a similar agency. The C&TS is unique that both offices need to approve ALL work, regardless of which side of the state line the structure is. A good deal of off-season planning by the Friends is to satisfy these needs.
To add a storage facility, the SHPO's would want to be involved with the location and appearance. They won't allow anything that is uncharactistic of the location and want new structures to "blend in", but not trick the visitor into thinking it is an original building. Examples are the dining facility at Osier, and I believe the Georgetown Loop's engine house at Idaho Springs. For restoration, they want the materials used and paint colors applied to match the desinated period , They even are involved with rolling stock work, we had to get approval for the 0579 to be turned back into a caboose from the tourist information booth that sat at the entrance to the Antonito yard.
We could debate whether hiding a metal building on the old saw mill site in Chama should need consideration, but certainly doing anything below the Chama yard would take a lot of scrutiny. I was told 2nd hand that the proposed pole building at Antonito needed a pitched roof, presumably to blend in with Ft Knox (the old storage building that was once part of the saw mill on that site).
The Friends involvement with the SHPOs started off a little rocky since we didn't understand them and they didn't understand railroads, But over the years I think both have learned a lot from each other.