Have you considered a Reese Goosebox to replace your pinbox, then simply hitch onto the ball in your bed? I am currently happy with my Andersen, but the Goosebox eliminates the frame footprint in the truck bed.
Look for a Bluetooth transmitter that plugs into the headphone jack on the stereo. Connect your wireless Bluetooth speakers to this and you will have music.
Something similar to this: https://www.amazon.com/Wireless-Backup-Waterproof-Reverse-License/dp/B078N5NZPW/ref=sr_1_13?ie=UTF8&qid=1545175994&sr=8-13&keywords=wireless+rear+view+camera+for+truck
