Is it reasonable to create a 30amp branch circuit for the purpose of feeding the panel from a generator?
NO.  

What you are describing could potentially kill the folks that are trying to help restore power to your home.  You're also creating a situation where you could easily overload your generator.

To do this the right way, you'll need to install a transfer switch. Transfer switches allow you to switch between two source of electricity, while mitigating any hazards associated with using a secondary source of power.

The transfer switch will be wired in such a way, that backfeeding and/or overloading the generator will be prevented (without a lengthy start up procedure). Once the transfer switch is installed, you'll simply have to...


Connect the generator to the inlet in the garage.
Start the generator.
Flip the switch(es) at the transfer to the GEN position.