I don't believe they can - they mount entirely different, hooking to the muffler hangers, and inside of the fender, to the bag mounts somehow. I can't remember exactly all the ins and outs, but a buddy has a 1500 wing, with hitch, and I tried very hard to figure out how to build one that would work. I do quite a bit of fabrication, and engineering, and just wasn't feasible. Same one I tried to figure out how to adapt the center stand to the Valk. Another no-go...
There IS one hitch, I believe it's made in Australia, that mounts "similar" to the Wing. But, I've never seen any good pictures, or one in person. And if I recall, it was VERY expensive.
Just curious - do you have access to a Wing hitch, or are you trying to mimic the "invisibility" of it?
EDIT - Here's a link to either the Australian one, or one just like it - it mounts up by the front of the swing arm, and has two "hangers" that mount to the back rails, if I recall:
http://www.hellrisercustoms.com/bikes/valkyrie/category/Frames/subcat/Hitch-Towbar/maker/CIAU/item/CI-TH27Roger