Yea, I agree that a lot of OEM receivers are getting difficult to work with. They're designing them more and more to "blend in" with the design of the truck so they aren't so obvious when not in use, so they are tucked in and harder to reach. Had a similar problem with my 07 Expedition. I do seem to recall that I used a pin that had a groove in it rather than a hole. So you could put the pin in any direction. That helps with the problem you mentioned, but not the original lock problem.
You could try just using a grade 8 bolt, put it through the hole, put on a lock washer and tighten the nut down good. Maybe even drill a hole through end of the bolt that a small padlock would fit through. Make getting it off hard enough and the thrives may just pass you by for Ancaster target.