Austria - GO-Box - easy to avoid motorways?

Good morning again! Sorry yet another question!

If you have a motorhome over 3.5t and you need to have a Go-Box to use the motorways and expressways in Austria, how easy it is to stay on the minor roads and avoid the ones you have to pay for?

Are the minor roads big/wide enough for motorhomes? Is is easy to navigate around Austria without using the roads that require a GO-Box?

Any feedback for advice would be most welcome!