It seems I had overlooked the usefulness of the "Edit and Continue" option (Tools -> Options -> Debugging -> Edit and Continue) after struggling to get past the infernal dialog message:
Changes are not allowed in the following cases:
- When the debugger has been attached to an already running process.
- The code being debugged was optimized at build or run time.
- The assembly being debugged is loaded as domain-neutral.
- The assembly being debugged was loaded through reflection.
Despite having the option checked in VS options you have to enable it for each separate web application. In the Properties Page it's on the Web tab when you scroll right to the bottom "Enable Edit and Continue".
Making small changes using Edit and Continue isn't exactly the same as making code-behind changes to a Website project, however, it's far more palatable than restarting the app for every code change.