The overhangs in the front are about 5 feet from the ground, it seems like it would be very easy to physically disable them if someone tried. What other options would there be to keep it at 15 feet, just buy a more expensive camera with a larger sensor?
That's the whole point of having the cameras positioned so they're watching each other. There's no way to get to them without being recorded. There's also no reason to mount them under the overhangs unless your wife insists on being discreet. I'd actually suggest you mount them on the face of the wall because the overhang may prevent a facial view of someone who's tall if the cameras only at 5ft as it will clip the view looking along the wall rendering them useless. There probably are ways you could disguise them on the face if you really required it.
If you're worried someone might disable them and then get into the house without you being able to prove break and enter, then you could put an Aneke Cube inside the house. Nice and cheap will prove the intrusion. Search the forum for more info on this camera.
Also, from the corners of the house you probably won't get a good face pic at the door either with a 2mp camera (which is the best resolution for night vision (starlight cams)). Take a look at what many on here consider to be the best night time camera the HDW5231R-ZE - the Identify parameter on Wide angle is 13 feet max. If the diagonal from the camera to the door at 6ft is more than 13 feet, then bang goes identification:
IPC-HDW5231R-ZE
Ok if someone walks up the side of your house, but maybe too far back if someone walks and makes a bee line for your door across the lawn. There's a lot to be said for having coverage at the door and then building the rest of the system backwards from that in my opinion. You're somewhat unlucky in that your door is recessed making it harder to get the coverage you want with fewer cameras. Other way is you could have 1 camera on wide and the other on zoom to increase the identify distance, however, zooming will also cut the field of view and area covered. This is the way I plan to eventually cover my own backdoor but the side of my house is only around 35 feet. Final way would be a
door bell camera in addition to the others, but the pics are usually awful compared to "proper" camera.