I'm working on hanging a stainless steel sink between my frame rails to hold 1-2 batteries.
I want the AGM I have to be able to vent if required and drain if immersed, and an $89 sink seems to fit the bill.
It's located with a few rivnuts through the floor of the cab, but supported by a length of uni-strut bolted to the frame.
I've cut in a Bluesea weatherproof breaker to protect the line coming out & shut off the system if required.
All the other electronics are inside the cab under the rear passenger seat, warm & dry.
I have to use a jack to raise the enclosure and attach it, but my hope is that I will not have to access the battery while I'm on the road.
The battery sits on a square of plywood and is secured with a few more pieces of wood, so I expect the sink to be able to take a few scrapes and bumps without doing any harm.
With all the hardware, I suspect I've spent $130 so far & spent a good amount of time on my back trying to make it work.
A $200 bracket may be worth your time, but I would feel a little naked without some form of protection-