Dave, nothing wrong with being indecisive. I enjoyed the exercise, just sorry it's not going to work out. I had never made a serious attempt to model easements in SCARM, so it was a learning experience for me. I think Mark and John both said they did a lot of trial&error to get their grades running smoothly and that's not something you can do until you have an engine. I know Mark set up a test with track on a long board to see how high his engines could climb before we settled on his elevations.
Anyway, since there's so much track vs landscape space in the train room and only smaller engines will be running on the inside track, I did a little experimenting. I don't know if this would be something that could satisfy your desire for elevation changes, but I thought I show it.
The upper left purple track goes up 1". The blue on the other side is supposed to be purple too and it also goes up 1", both for a 1.9% grade. The lower left purple track goes up another 2" to 3" total for a 2.4% grade while the lower right purple track goes up another 1.5" to 2.5" total for a 2.2% grade. I don't think these will cause any problems for your smaller engines.
Obviously, that means one of the removable platforms across the entry will be at a slight angle. However, if you don't want that, you can simply lower the left grade to 2.5" instead of 3", if you decide to go this route. If you go up to 4" and 3.5", the grades change to 3.6% and 3.7%, into needing easements territory and closer to what you have with the trestle set.
Also, don't forget that there is at least one version of the Big Boy that runs on O-31 curves, the "MTH Railking O Scale Big Boy", though I don't know what that means as far as easements go. You can search for that and the "Premier" version to see the difference in price and detail. If that can use steeper easements and you can get to 2" for the left yard and 4" for the right yard, it might make sense. The SCARM file differs a bit from these photos because I played around after I did the captures.
