I have a 2024 F350 XL 7.3L Gas 4WD Short bed, Supercab with dual alternator (total 410A) and no uplifter switches

I am adding a DC 2 DC charging (50A) capability from the truck to a camper using Anderson connector.
The camper has LiFePO4 batteries.

To the truck engine bay, i added a 12V 150A continuous duty solenoid relay, which connects to the passenger side battery +ve, located next to the engine bay fuse box,
and a 20ft long 2ga cable towards the rear of the truck.

Question 1> I need an ignition run trigger from the fuse box next to it for the solenoid to turn on/off when the truck engine is running.
Where in that fuse box, should i tap in? Is there a fuse location number? I do have the micro-fuse tap kit. I donot have up lifter switches in this truck.

Question 2> The 2ga +ve battery cable, about 20ft long, is running from the solenoid relay to the rear of the truck, where the anderson 175A plug connector will be mounted.
I am not running a -ve battery cable this long, instead i want to tap into the ground for the chassis or the truck frame. I would like to use a "short" 2 awg ground cable
for this, running from the anderson plug to an appropriate ground point location. I am concerned about future rust issues, so trying to avoid drilling new holes.

Could one of you please share a photo of your 2023/2024 truck underneath with an existing ground location? It would be nice if i can just use an existing location to add my ground lug to it.
If not, i will have to drill, but that's my last resort. I have looked underneath my truck, near the hitch area but don't see any ground screws/lugs.