Ok, whie I can see the point there, and it may be "do-able" as a series of winter/off season projects (to get the rest of the "fleet" up to spec), I think we need to concider the availability of the rolling stock. Especially the passenger "fleet."
It might not be a bad idea to have at least one coach "extra" for when annother is down for conciderable maintenance that might take it out of service for most or all of a running-season.
Now, I realize that with the major rehabs done to most of the passenger stock as it's come in, it may be quite some time before anything will need to be so fully rebuilt that it'd be out of service for longer than a single off-season.
Just the same, I think it's a point worth be concidered.