I don't want you to do anything All I am doing is providing input and food for thought. FWIW, "hump" doesn't have to be aluminum, it can be (molded?) plastic. Or if you make your own umbrella adapter (nobody says you have to reuse Godox one) you wouldn't need "hump".
I don't see how "hump" I have in mind would prevent you from sliding the modifiers but maybe I don't see what you do and/or maybe you don't see what I have in mind.
Then just draw a picture of what your talking about and post it.