Fitting rear view camera in an INCA

Any help greatly appreciated...
I am about to fit twin rear cameras to our 2005 AutoSleeper Inca [on a Peugeot Boxer base].

Any ideas on how to get the wiring from the high level brake light area through to the headlining by the rear view mirror? Also, I need to connect to the reversing light - but I may have to pick up that supply from the cab area.

TIA

stevie b

The alternative might be to pick up the reversing signal from the rear light clusters, under the skirt and to take the camera feed forward via the chassis and up into the dash from below.

If not, I'd be taking the headlining panels down one by one to feed the wires through.

Thanks, MeanChris -
Is the headlining hard to remove/replace and do you know if it's easy to access the rear of the vehicle to feed wiring, please?

Unfortunately ours is a monocoque Executive, so constructed differently from an Inca.

Our (wireless) camera was fitted by drilling a hole through the shell above the high level brake light and connecting the power supply wires into the 12V supply for the rear lights, as I wanted the option to have the camera on permanently (although of course that means sidelights on, which also means that it's unlikely that I'll leave the camera powered and flatten the battery).

I was considering a wired camera at the time, and looked at the routes available for the wiring, deciding that under the chassis was probably better than removing the individual roof lining panels which (in my vehicle) are held up by capped screws onto a wooden frame.
It's also possible to use the lighting wires as guides, by removing the light fittings and poking a guide wire through the holes in the battens, I've done this to install a low current supply for a 12V socket above the cab for a TV and Sat box.

Unless someone has a better method, I think that you'll have to look at both options and their potential pitfalls (like how to get the camera wires down the inside of the back of the van and past the floor where it meets the shell for example). I've also had the above kitchen cupboards out in this current van, to access the insulation and wiring to add spotlights above the sink and cooker. It's all doable, with some cursing and sweat.
Sorry I can't be more specific.

I have a Dorset so a van conversion and fitted twin camera last year (but have done quite a few now) so may be different to yours.
Started with fitting above high level brake light (after painting over top quarter of brake light to stop glare when braking) via the high brake light opening fed the cable down the side of the van that had the fridge grill which I removed to get access to the lower cupboards so that I could get the cable back inside the van, after a couple more internal holes I then fed the cable back up the door pillows across the windscreen top to the mirror monitor. Power cable back to fuse box followed the same route. Admit it took quite a bit of time but all wiring out of sight and inside so no outside cable problems.
It  was when I was doing this on the Dorset I found out how much better put together the van was than my previous Tribute (although following a similar route on the Tribby I had to do no drilling plenty of gaps.
David

Thank you for your replies & the information contained therein - looks a bit more involved than I first thought!
I think the easiest way will be to drop down behind the rear, pick up reversing light supply, then carry on under the chassis, but we'll see! I'll let you know when it's done. Thanks again.
Steve