There are surface mount 12v outlets, I got one at a local auto parts store and installed it in the drivers side glove box of my 2008 FJ to provide a plugin for my GPS. All you need to do is decide where to put the hole (and make sure you have access to the back of the hole). I had a more substantial version of this, I can't find one on Amazon quite like what I used:If you want to hard mount the 12v outlet (not necessary), you will need to fabricate/buy a mounting flange (3d printing may be an option).
This was over simplified and not my intention to insult anyone's skill set.
Amazon.com