Two $70 Dahua IPC-HDW4431C-A turrets @ 4mp for 8mp? Mix the lenses up and, for instance, get a broad view of your driveway and lawn with a 3.6mm and ID detail in the driveway with a 6 or 8mm. With twice the IR you'll get even better low light performance.
I don't know of any decent cams that completely meet your requirements. If night performance is very important to you, get yourself one of these for a few dollars over your budget-
Dahua Starlight Varifocal Turret (IPC-HDW5231R-Z)
The improvement in night-time picture detail will gain you more than you lose in the day to the lower pixel count, particularly if low light performance is most important.