My prior trucks were Duramax's so NO room under the hood... I've always installed the compressor in the bed of the truck on the PS wall all the way forward under my tool box. I run a tool box and tonneau cover. The Viairs are hearty and can handle the elements though. 2.5 gallon tank usually on passenger frame. This time I was able to put tank under the bed and compressor under the hood. 2 or 2.5 gallon tank is enough. No need for a 5 gallon tank as the recovery of these smaller compressors is too slow.. If you want a fast hearty compressor, you need a belt driven one, like a sanden AC compressor converted to air. I ran this set up on my jeeps many times...
The air chuck in fuel door with a few fender washers. Tank and compressor. I have used push in air fittings and 3/8 line and then 1/4 line to air horn, and a foot switch. I'm converting all the fittings to compression fittings. the push in tend to leak and keep the compressor running alot. A simple chair foot cap, to keep the air chuck clean from debris