Hi,
Yes we have contemplated a lot on doing something very much in the spirit of what you need.
Actually I don't know if you have seen the early posts about the
new API but we have invested a lot of thought on coming up with ideas on how to help in these exact situations.
For example, one of the possibilities that will be available under the new API is to construct a fake that will always return a default value. This will allow you to define an instance (that you don't really care how it used or what it returns) be fully operational in a single line.
:idea: Try looking at the Isolator
Custom Decorator, if you have some time and feel up to it, you can use those to extend the isolator framework to do exactly what you need.