I've never had a tow hitch before. What kind of mount are people getting for the tow receiver that comes with the towing package on the Model X? I was talking with a Model S owner who had a tow hitch on his S and he said I need to know the height of the trailer I'd be towing to know what mount to buy., especially since the tow receiver on the X is relatively low on the X like on his S. My problem is I don't have a trailer. I will most likely rent one when I need it. So do I wait until I rent a trailer to figure out what kind of ball mount to buy? I see there are adjustable ball mounts. Is this a good option for someone that doesn't have a specific trailer to tow? Will all 2" mounts work on the 2" receiver on the X?