Backup cam, truck cap wiring

2013 outdoorsman. Have a couple projects pending.

1 replacing drop in bed liner with bedrug. Already ordered bedrug should be here in a couple days.

2. Also just got New leer 100rcc cap. Local leer dealer did a poor job wiring to tail light. I do not like it. I have read that I can hook up a leer 7 wire harness to my tow wiri ng harness. I have both 4 and 7 pin plugs in bumper above hitch. Don't want to spend $60-$80 on Lear harness, any suggestions? Mostly I want to be able to turn on led light bars in cap without having to turn truck lights on, would also be cool if it turned on when I turned on cargo lamps. Problem is leer seams to have all there specifications and parts only through dealer network. Anyone done this with aftermarket wiring harness?

3. Tool boxes/ bedslide/ shelf
Debating several cap organizers, 1, leer locker, cap ceiling noted slide out try. Like the use, but anyone have an opinion. Tool boxes for side access doors, dealer wants $90 each side, but i have to install. I am tbinking of building my own boxes, loot to ceiling with an open shelf from inside bed above both wheel wheels, deep 16" tool boxes above. Need to leave at least 4' wide on floor for plywood, sheetrock etc. Anyone have the leer boxes, are they hard to install? Would really appreciate it if anyone could send dimension and some pics from inside and out?

Can not help with 1 or 2 but 3 I can throw in my 2 cents if your interested !
For years in ran a pick up with a cap, and it had 1 big side door each side to get my parts ! I am assuming sort of like yours ! I use a slotted steel angle metal, and sized it to fit my parts. Line the bottom with plywood, also used the anit vibration nuts. worked well and you can always change the size of the shelf ! access inside or out ! Also you can find the metal used and a way cheaper price from a warehouse or anyone who made shelves! Hope this helps, Not fancy but works and the price is right lol

I used metal like this

https://www.my365hardware.com/618926.html?gclid=CISb8uSowtQCFZNKDQodP-MGnw

https://search.yahoo.com/yhs/search?p=perforated+angle+steel&ei=UTF-8&hspart=mozilla&hsimp=yhs-004

Do you have a pic or link to the Leer harness adapter??? I bought an adapter that plugs in on the backside of my 7 pin then T's out to a 4 pin to which I plugged my LED brake light strip.

Mine looks like this: https://www.etrailer.com/Custom-Fit-Vehicle-Wiring/Curt/C55384.html

If your Leer is like mine(100XL), there is a fuse panel on the left side for the cap lights, door lock and third brake light interface.
My dealer wired the cap light power to the 12V in the 7 pin harness. I added additional LED strip lights to the cap. The brake light interface can be wired to the left and right turn/stop lights, the 3rd brake light only lights if both are on. My dealer actually used the 3rd brake light wire(purple/white) that is under the truck by the spare.

Apparently the leer part works like the Curtis, plugs into back of 7 pin and runs up to fuse box in cap. Not sure it's worth the effort now that I think about it. I almost never work in bed at night, and how much of pain is it really to turn on truck lights to operate dome light. What would make it worth it would be a. 120v outlet in cap to charge batteries. My outdoorsman has the 120v plug on dash, very convenient. Can only charge 1 battery at a time , but not bad. I think I will build some open shelves with the aluminum angle iron, Closed around tool boxes but open underneath for access from bed. Or perhaps open all the way around to reach in or out. Anyone have the leer tool boxes and that locker under cap roof deal. If the factory boxes are functional I can get them for $90 each?

so I wired the cap. was not happy with installers rig. I found 12v hot and ground wire in trailer harness and ran it to dome light, the hot wire also went to third brake light. cargo led light is working on previously installed switch and has constant power, the only problem is the now the 3rd brake is still wired to tail light, so it blinks when I turn left. wondering if I just tap into brake light on 7 pin harness. I believe the stop an trun signal is on same wire to both tails and 7 pin harness. also, cap came with built in fuse block, two 5amp inputs, 1 chmsl / dome out, and 1 chasis out. looks like two 4pn sockets on top of block. so constant hot from 7 pin harness to 1 of the 5amp feeds, ground to chasis, and stop light to other 5amp? wondering if that block somehow stops third brake from blinking. maybe better to just find the third brake wire going to cab mounted light, tap into it and run back directly to third brake light, bypassing everything else. just use trailer harness for constant power to dome light.