Creating a 'Virtual Switch' to Operate an Outlet

That should work. There are also a couple of battery operated switches that you can just put on the wall if you prefer that.

BTW, you could still just use a plug-in pocket socket inside the cabinet if you want, those can also be controlled by any other device on the SmartThings network, including another switch or a button. So pressing on the wall switch sends a message to tell the pocket socket inside the wall to turn on.

Here’s the list of buttons and remotes that currently work with SmartThings. You can see if any of those look appealing to you. At least one of them is mains- powered, but most of them work on battery.