Can I install a switch upstream of my service panel for regular shuttoff duty?
A much better plan would be to install a subpanel near the service panel.  

Then, move the circuits you want to shut off to this new subpanel.  

At that point, you have two ways to solve it: First, the individual breakers in the new subpanel could be SWD.  Second, you could shut the feed breaker off to the subpanel. 

Depending on the subpanel, you could also install Arc Fault protection, which will help a fair bit with animals chewing on wires and feisty old devices.  I presume there is already a whole-house RCD.