They are IP67, so they should be able to withstand the outdoors. They also feel quite solidly built - it has a heft to it!
I am not a fan of Wifi extenders - would rather look at a mesh network or perhaps look into Powerline Ethernet (AV600/AV1000)? You will have to run 12v to the camera in any case, and running a shorter stretch of ethernet cable from a the spot where you plug in the 12v adapter is perhaps quite doable?
One thing I should note – the camera you see earlier is connected via ethernet. Wifi reception in this case was also not great and we took the trouble to lay ethernet.
That being said, I really haven’t thought of using Powerline ethernet up to now – it is something that I might test with the hard-to-reach spots at my own place too!