2005 RX330 bluetooth cam installation

[Frazzled]

New member here. Hope the group can help!

I own a 2005 RX 330.

I have purchased a bluetooth backup cam (DoHonest HD rear/front cam & monitor).
It can function wirelessly with the power tied into the backup lights, or a wire can be run to a power source in the cigarette lighter.

I've taken off the 2 panels inside the lift gate and it's not obvious which wire i should use.
I can't find a tutorial for my model anywhere online.

I tried to drill a hole above the license plate in order to install it with the wire, but I guess I don't have the right drill bits for the metal.
I can't figure out any other access holes that I can use.

The most significant thing is that the wire has this wide/flat part just before the four pin connector measuring about 3mm x 9mm that has to also pass though the hole.

It's a car that I bought for $1500 so I'm not afraid to do something unconventional, but would prefer that it didn't negatively impact resale.

I will be doing this myself and alone.
I would appreciate suggestions which adhere to those parameters, especially video links solving this problem with the same or similar model.

Thanks for playing, and forgive me if I've overlooked a duplicate thread.

[RX400h]

I've used something like this to check wire positive voltage:

https://www.amazon.com/ALLOSUN-GK5225-Automotive-Piercing-Indicator/dp/B07WG7912B/ref=asc_df_B07WG7912B/?tag=bingshoppinga-20&linkCode=df0&hvadid=&hvpos=&hvnetw=o&hvrand=&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=&hvtargid=pla-4583863985028591&psc=1

There are also non-contact testers that are a bit more expensive. You ground the tester's black wire and then check car wires for 12V when someone is stepping on the brake pedal.

To drill a round hole large enough for the connector, you'd have to start with a smaller drill (3mm/1/8-inch) or so and work your way up to a large enough hole. A rubber grommet is highly advisable, as is painting bare areas of the hole to prevent rust. You may be able to use a Dremel tool once the hole is large enough for an abrasive bit to slip in. Steel can be tough to drill through so have a couple of each size drill (new or unworn used).

 

[Frazzled]

Good suggestions! Thanks.

[RX400h]

I forgot to mention that before drilling a hole, it is helpful to use a drill center punch like this:
https://www.amazon.com/Neiko-02638A-Automatic-Center-Adjustable/dp/B008DXYOLC/ref=sr_1_5?crid=1J37T3ZB0U92U&dchild=1&keywords=drill+punch+tool&qid=1598912139&sprefix=drill+punch%2Caps%2C214&sr=8-5

Of course, if you planned to be using one often, then a more expensive version (like one made by Starrett) would be preferable.
This type of tool is "automatic" because it is spring loaded, meaning after you locate the desired indentation location, you place the pointy tip at that location and push on the opposite end. The pointed end will be sprung against the material into which you wish to drill, causing the indentation. 
 Subsequent drilling with the first (smaller-sized) drill bit be will be less likely to allow the bit to wander as it is spinning.