There is not a pigtail as such. You can install a fifth wheel wiring connector that splices into your under-bumper plug. It has a long enough extension to allow you to mount a plug in your bed. There is no wire cutting or splicing needed.
Like this one
Compare Pollak Custom Fit Vehicle Wiring vs Draw-Tite Custom Fit Vehicle Wiring | etrailer.com
Like this one
Compare Pollak Custom Fit Vehicle Wiring vs Draw-Tite Custom Fit Vehicle Wiring | etrailer.com