People are already developing aftermarket parts for the Cybertruck!
Behold! The Cyber Hitch, "non-intrusive (flush mount), full-motion 5th-wheel hitch". It would accommodate a gooseneck-style trailer. The hitch is located in the bed of the truck instead of by the back bumper.
It uses a 6-inch diameter coupler with a 2" kingpin. The master locking lever has 2 independent spring-loaded locking pins for the kingpin. The creator of the hitch claims it has a towing capacity of 16,000 pounds but has future considerations of up to 30,000 pounds.