Get a new male plug and cut off the old one, then install the new one.
https://www.amazon.com/Camco-PowerGr...co+50+amp+plug
Then purchase a right angle adapter for the trailer end so the cable hangs straight.
https://www.amazon.com/Camco-55572-L...co+50+amp+plug
This should solve your issues and will prevent stress on the cable jacket.