I would go buy a replacement unit.
https://www.amazon.com/Travel-Trailer-Entry-Paddle-Deadbolt/dp/B0787DZDHT/ref=pd_sbs_60_t_1/137-0545791-3227819?_encoding=UTF8&pd_rd_i=B0787DZDHT&pd_rd_r=97c78656-c20e-46b3-874e-5ed4eb5a4cd9&pd_rd_w=kwrHF&pd_rd_wg=ahF3A&pf_rd_p=5cfcfe89-300f-47d2-b1ad-a4e27203a02a&pf_rd_r=JAJZ484X87MEPD2NSEP1&psc=1&refRID=JAJZ484X87MEPD2NSEP1And study how it works before attacking the one on the trailer door. The lock in the movable handle is not the best way to lock you rig BTW. The other lock is the dead bolt, which works only with your key. The lock on the movable handle works with universal master keys that dealers have.
Study how the new one works might give you a clue how to best destroy the one on the door so that you can get in.
You also might try again with your key holding pressure up or down(one direction or the other) on the key as you turn it. I believe if I remember correctly, that the key slot is horizontal when locked and vertical when unlocked. Have you tried pushing in on the door with the key slot vertical, while trying to open the door. Maybe the latch is just under pressure on the striking plate on the door jam.
Chris