The issue you are having with completing curves using Ross track is one reason that I went with Atlas for most of my layout. I still need to use Ross #6 curved switches in my staging tracks and to cut curves to complete the 90 degree change in direction at each end. Why Ross couldn't use standardized it's degrees of curvature is a mystery.
I've read that Ross will do custom work. I don't know what it would cost but it might be worth taking them up on it in the future.
Jan