So what's distance from nearest camera point to where car is parked , I assume distance becomes shorter?
Maybe do an overhead drawing
By the way if your going DIY hiwatch is probably the equipment you may want to use , but with a full size recorder not the little square box in some kits , they are hybrid versions so you can fit diff cams to them depending on what you need
Shame you don't have budget £2500 ? Do it once get contractor in?
Your far from Manchester ? I sure someone near you can give you a quote less hassle for you but whatever DIY it if you have to