Currently, one route uses one option, mixing is not possible. We are aware of the limitation and are looking for ways to improve this.
In the meantime, we recommend to split the routes into multiple parts. A common example is to travel fast to a nice curvy area and then enjoy curves there. So you would create one part for travelling to the area you want to ride in with the fastest option and one part for the actual fun part with the curvy or extra curvy option.
If you save these routes as .kurviger files it is easy to load them in the app and you don't need to switch between the options for loading these files, this is done automatically. Loading .kurviger files can be done without mobile reception. We recommend to combine this with a fuel stop or a short break so that you don't need to stop just for switching the routes.
For short motorway passages you could just put up a couple of waypoints on the motorway.