Wiring from cabin to boot

Hello everyone, i've had a look at some other posts and can see people have answered this before but i can't quite get my head around it (doesn't help that the photos are missing on some of the more detailed posts) so apologies for asking this.

I've replaced the head unit in my TF and as it came with a reversing camera i figured i might as well install it, i do have to do quite an intricate manoeuvre to get into the side part of my drive so it'll come in handy there at least anyway. I think i'm pretty sure how to wire it using the reversing light for powering the camera and triggering the head unit to switch to the feed, and i've done the easy part of getting the wire from the dash to the rear of the passenger seat. I've also found a large grommit that looks perfect for getting said wire from the engine bay to the boot but i can't figure out how to get it from behind the seat into the engine bay in the first place, i tried pulling back some of the lining in places looking for an obvious way in but i can't see anything.
So what i'm after is an "explain like i'm 5" interpretation of where i need to go with the wire to reach my next target of the engine bay from behind the passenger seat, once its in there i'm planning to use the large grommit towards the mid left to come through into the boot and then i assume to get outside i'll need to pick somewhere to drill? or is there another way to get to the outside?

Thanks in advance for your help everyone.

I fitted a low coolant kit..highly reccomended and had to run a wire from the rear to behind the drivers seat..the opposite of what you are doing.
You can run the cable under the carpet along the sill and up the side of the carpet behind either seat..under the door trim if need be..then under the T-bar ...you can get it thru in to the engine cover/shelf and from there thru a large grommet on the shelf to the engine bay and by removing the boot carpet along the inner wing to the resr panel.

Ok, so... remove the T-Bar (i assume remove wind deflector first) and i should see a grommet leading through to the engine bay, i assume i'll then have to take off the engine cover (not done this or the T-Bar yet so all new to me) to reach the wire poking out and pull it through to the other grommet i found to bring it into the boot, from there i can wire into the reverse light (green/brown wire from what i've read) and ground (presumably black) before sending the wires out to the camera, and you say theres access to the rear through the wing without having to drill?

Thanks for the help as ever

No!
You don't need to remove the T-bar..if you remove the engine cover carpet and then the insulation...commonly know around here as the dead dog..you can see a way under the T-bar....you will see the large grommet which you can poke a wire thru on the side of the shelf in to the engine bay.
Whilst there take a good look at your engine..nice looking motors.

fantastic, i'll take a look tomorrow and see if i can get further, thanks

Might I offer an alternative? If you run your wire via the drivers side
You can follow the bonnet pop cable & utilise the bulkhead holes accordingly.
I’m pleased to see that little yellow car on your thumbnail, welcome aboard, you have already sampled the rest of the crew; a better group of old salts you couldn’t wish to meet on a mess deck.
If you are intending to pick up the reverse light voltage to enable your system, I would be inclined to solder a wire on to the appropriate connector on the bulb board.
You are well advised to grind the top surface from the contact strip before tinning the strip.
M

I was about to suggest you do exactly what Airportable suggests.  If you get a low coolant alarm kit the instructions will direct you to use this route.  No need to remove The-T-Bar.  No need to remove the engine cover either, unless you need to get at the reversing light connections.