It should not be difficult to release the latch from the kingpin.
Can you identify which locking style you have? A, B, C or D or other if there is one.
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The clamshell WILL be forced open by the kingpin when hitching. As you push the kingpin into the jaws the arm will extend. I believe the clamshell style is best as I always knew when the kingpin was fully seated in the hitch as the handle would snap into the return position when fully seated.
It seems to me that the only time there was a need for any force is when the trailer is pulling toward the rear against the locking jaws. If you block the RV wheels at the rear and push the trailer/truck against the blocks, the pressure should be released and the arm should release easily.
I do not know the operation of the other types of latches.