I think the outlet/switch on the inside and the single switch on the outside would be the way to go. You would not have the power plug in the way by the switch.
Also you can use a rocker type switch so you can make a large button to activate the switch easily if you need to shut the router down in a hurry. If something unexpected happens a small switch might be hard to get your hand on.
You could use a safety switch on the outside like the ones sold by Rockler and MLCS.
Hope this is of some help,
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