There is compromise in every design.
A safety factor of 1 will work, but it doesn't allow any room for error or overload.
I prefer to minimize stress on all the parts & have as large a 'safety' factor as possible. Hence this discussion. I didn't say Glenn's hitch would fail. But, Glenn asked for input & input is what he got.
How he chooses to proceed is, hopefully, his business only. Like most everything else, if he chooses well, he will have success. If he chooses poorly, he will gain experience.
My '94 Explorer had the towing package & a receiver hitch bolted to the frame . After an unintentional overload was applied, the hitch was fine, but the frame was bent (over the rear axle a couple of feet past where the hitch was bolted). So while the hitch survived, the system failed.
The frame wasn't able to handle the load the hitch was able to transfer. If the hitch had transferred the load differently, the frame wouldn't have seen as much stress, but the hitch would have cost more, hence the compromise. . . .
Quality hardware is a must. So is routine maintenance of checking the bolts - especially at first to establish a base.
Craig, what is the reason for not using gr8 hardware? I'd rather not miss something. . . . but I thought it related to cost. In my designs, I try to design around gr2 hardware to prevent failure caused someone using weaker replacement hardware . . . . You may be surprised at how many don't know the difference.