My 2022 F350 install. I had my local (2-hour drive) FWC dealer drill the holes and do the wiring from the engine compartment to the cargo box. Like you, I thought about doing it myself but decided after spending $75K on the truck, another $740 was little to pay for the peace of mind. That said, FWC does have a video on their web site that explains exactly where and how to drill the holes for the eye bolts -
The backing plates are a different story. Given the aluminum body, I wanted a stronger, more rigid anchor for the camper than what is normally supplied by FWC. This was my preference and I tend to overbuild everything I work on. I fabricated my own backing plates out of ¼” aluminum plate and sized them so they would span under a cross member (or two when available) below the bed of the truck for more strength.
The image below shows the FWC backing plate circled in red. The custom fab plates circled in purple are for the front of the camper, and the plates for the back of the camper are circled in green. For added strength I also installed the FWC backing plates on top (see pics) of my custom fab plates. I also fabricated plates that go in the top of the bed (circled in black). The eye bolt holes are drilled in the low part of the ribbing of the bed and the fab plate goes into that part of the bed so a fender washer can lay flush on the top of the bed ribbing. It also spreads the stress forces over a greater area of the bed.
If you decide to use additional backing plates under or above the bed, make sure all of the edges and corners are rounded off to prevent the backing plates from cutting into the bed. If you do all these things, you will need to get longer eye bolts to span all the backing plates.
Installing the backing plates is straight forward. The most difficult plate is the driver’s side front plate. The only way to get the plate into position is to slide it across the top of the fuel tank starting above the drive shaft. It’s a pain in the behind but can be done. See images below for final installation of the front backing plates. Sorry, I don’t have pics of the rear ones and the truck has already been put into storage for the season.