I hardly if ever use my cargo area with the rear seats folded down so I have mine mounted (one to drive my subs and the other to drive my door mount speakers) on the back of each rear seat. Aesthetically clean, completely hidden out of sight especially if you have a tonneau cover. Works great for me.
I won't tell you to do this but it worked for me. I had a JL 250/1 under the rear passenger seat where the Jack is located. I actually never had it overheat either.