Do it yourself.
Headunit will be plug and play, just make sure you get some harnesses.
Get a 2DIN kit.
SWC should not be an issue with the latest HU as they can "understand" Subaru's signals. Failing that you can always get a decent SWC control unit off amazon/ebay cheaply, wiring is not that hard.
Cameras are cheap too and are easy enough to install, just find a wiring diagram and find out what/where reverse gear signal wire is so you do not have to run the wiring all the way from the taillights.