Transit reversing camera

As title; I'm looking for a suitable one for my ELWB Mk 7 Transit campervan - it's not got rear windows so reversing's a bit of a pain.

Ideally I'd like a twin camera setup which gives a rear view as well as the area immediately behind the van for reversing manoeuvres. I've not found much advice when I've Googled it.

Part of the problem is the doors extend up to the roof so there's nowhere to fix a camera kit to the rear. It'd have to be a roof-mounted system and I've not found one with twin cameras so far. If not, does anyone have a recommendation for a good roof-mounted single camera (ie reversing only)?

Thanks in advance

Thanks for the comments. Are the ones from China delivered in reasonable time?

TBH there are so many companies out there flogging them it's a bit confusing, and opinions vary from 'cheap is fine' to 'you get what you pay for'