Sorry for the delay in answering about the 'SKS tour' comment.

As you might very well know your Prius has 5 antenna's ( proximity sensors) located in the two front doors, roof, rear hatch and driver side rear wwheel well. The locations are shown in your manual.

These 5 sensors are searching 24/7 for your key fob. They run off the 12v battery. Again in your manual it suggests disabling your SKS if you will not be using the vehicle for up to a week. Use the button under the steering column.

If however you are going to be away longer than 10 days then Toyota in a TSB recommends shutting the whole system down by disconnecting the wiring harness which goes from the 12v battery to the positive terminal in the fuse box.

I tell clients from 1-2 weeks just disable the SKS using the button.
From 2-4 weeks it's a personal choice if you want to disconnet the wiring harness. Toyota recommends it but others have said they've had no problems after coming back from a trip or vacation.
For any time frame longer than 4 weeks I'd definitely shut the whole system down. One client brought hers in for service just before going on vaction for 4 weeks and asked the Service Dept to shut it down.

Lifetime fuel usage: 2.1 GPC ( 1.99 recent )