My suggestion would be to switch over to the round 7-pin connector typically utilized in the trucking industry. I purposely ordered mine from a supply source that catered to over the road trucks to be certain that I was getting heavy duty units. With my most recent conversion, I went with Dell City and the product appears identical to what I purchased at the truck specialty outlet. The following components are what I purchased for my Overlander:
Good luck with your investigation!
P.S.: I have used this setup for four years now with excellent results. The tow vehicle end hasn't had to be disassembled and cleaned nor has the trailer end . . . that was an annual task with my old blade connectors . . . and the connectors often had to be replaced after the third year with the blade-type on my vehicles. The pin connectors are still trouble free at four years. I will probably disassemble them this year just to verify that all is well internally on both units, but I don' have any reason to think otherwise.