Im hoping to add a 12v power socket somewhere under the passenger seat. Ive done this before in older cars by just tapping into existing 12v socket in centre console. 

 

Im unsure that this can be done in newer cars. Anyone added 12v power in their skodas? 

It's not rear 12 Volt sockets, but this guide about retrofitting rear USB ports into the back of the central console might help.