Thanks for the info. My cousin has said he’d do the front one for me but the rear can be a pig of a job.
I agree with what Daver1rs said, the rear is just as easy as installing the front. Plenty of places to hide the cable in the rubber around the doors, edge of the roof lining, and joins in the window pillars.
Funnily enough I also have the same Nextbase 522GW front and rear camera. It's a great above-average dashcam, there are others out there which are a little better but it's far better than the majority of sub £100 dashcams. Only issue I have is that the rear camera is a bit rubbish at staying in place