I built the Italeri kit years ago and didn't know any diffierant so just left it. The Hase kit has those mounts moded onto the wings but they are just solid plastic. You can just make them out on this pic.
The only referance pics i could find were on line plus a small section on the 111 on a bok about the 321 glider.
If i was going to do what your doing, i would drill holes into the mounts and insert some wire into them with a spring around it, it does look like a spring in that referance pic.
Thats going to be a bg display, will look forward to seeing that.
I am a Norfolk man and i glory in being so
On the bench: Airfix 1/72nd Harrier GR.3/Fujimi 1/72nd Ju 87D-3