A technique described in this thread may help if it’s sticking to the trailer. (Rogue Wave’s post #5)
Launching On Dry Land!!!!!!
“The trailer is still attached to the car and the car has it's handbrake on.
Take the winch strap and extend the strap fully then run it underneath the boat and wrap it around a chassis beam and return it to the u bolt on the bow.
Start winching the strap in , this will then start to pull the boat off the trailer in a controlled and steady manner.”
I tried a similar technique and it worked a treat.