We did discuss it. And in some ways, planning a charter in late August is easier - daily ridership is lower compared to a Sunday in fall colors, for example. But Railfest operates from Thursday to Monday, which would put anything we did mid-week.
The other factor is the chance to cooperate with the Heber Valley and the D&S on the September events. All things considered, we went with September instead of August.
Like JBW said, one day we hope to put on some freight train events that will really thrill railfans like us as well as serve an interpretive goal. (We joke a lot about the "60-car freight train" we want to run one day.) It's going to be a while, though - there's still a lot of catch-up maintenance to be done on the freight car fleet, not to mention the restoration work.
JAC