Yeah in 1:1 size the A139 will fit on a phone screen, even a older phone with a smaller screen and bezels galore.
It is a little wider than the wedge cameras i have been dealing with over the years, but its size are no problem.
But due to its with, even if you mount the upper parts of the camera on a shaded area of a windscreen, then the bottom part that stick out will be larger, so different / more than old school wedge cameras, but not something that is a deal breaker in any way, you will have to be in a very special place to not be able to mount the A139 and have a stealthy install.
The very little plugs for the remote cameras do have me worried a bit, if you are the kind of person that take the camera off its mount very often / every day, you might want to stay clear off the A139.
Having cleaned my windscreen on the inside one time since i got the A139, what i did was just slide it off the mount and then using wire slack i draped it over my mirror so it could dangle there while i cleaned the glass.
So a good idea to have a little wire slack in the camera end, you could also unplug it all when you clean your window every 1 - 2 weeks, that i think will be fine.