Yes, my mistake, copper tubing.
The compressor noise in the cab is more concerning if you upgrade to an air locker down the road and it engages while your driving.
I originally wanted to mount my compressor internally but did not find a suitable location I liked. I settled for under the hood after much research on the ruggedness of these compressors.
As for encroachment into the cargo bay, it certainly takes up room where you could store several small sleeping bags, several gallons of water, etc. However, I traveled with a wife, a kid and a dog several thousand miles and camped for several weeks at a time, so my storage needs may vary from yours.
Each person determines what will be best for their application and needs, and of course we are each convinced its the best for us. This is “choice-supportive bias”.