Don't forget to check the weight of all that AC
I'd use 140 lb/CF.
The rotting previously suggested is a true concern.
Is the timber deck a single layer? Often that top surface is in 2 layers.
Is the deck going to drain OK?
When you say you would like feedback, does that mean you've had problems with your approach?
How do you bid a job like you describe?
I think your approach is a good one, providing you've got a good "Resident Engineer".
It wouldn't fly here in California anymore. Too many lawyers.
This can be done--and is done every day. What State are you in (geographically, not mentally)? The juristdiction usually has a maximum rate of change for superevevation. On Caltrans work the max. change is 6% per station.
Don't forget to watch the drainage with this concept. Often there can...
I've been using Autocad's/Softdesk/LDD for 12 years. While it can't make the surface models with the same complexity as Terramodel, (at least with the same speed)it is much easier to use and more "garden variety".
I primarily do highway engineering and site work.