Check out Dan Grec on The Road Chose Me YouTube channel. He installed an ARB compressor under the hood of his JT a week or so ago and shared the install video. There are links to the bracket in the comments.
I looked for the same thing but in the end decided it gets way to hot under the bonnet in Summer when the Jeep is towing the camper etc and the compressor would probably last but that heat has to shorten it's life I looked at the underseat one instead but in the end cheaped out and stuck with my kings twin compressor that has lasted for 5 tears so far
Really though, look at other locations, it gets super hot under there and the first water crossing covers it with crap....
I just completed the ARB dual compressor and AUX battery fitment using the American Adventure Labs brackets. Really happy with the result, but freight at the moment really sux.
Refer https://www.motortrend.com/news/al-oba-aux-batt-jl-2/ for fitting example.
A few changes since this article was made, including battery voltage display.
Personally, if I have a twin, I will consider MORE bracket or American adventure lab bracket...
Currently I have a single one, Im using the bracket as mentioned at #2. So far so good (1.5 years).
As per my research, lots of people mount theirs under the hood (at high position) since JK. So I have a faith with ARB for heat issues. Let's see how long it will last.