My concern would be the weight of the jet pack pulling the backplate downwards, and through this making the collar choke you :facepalm This may or may not be an issue with your light jet pack.
But if you go through with it, how about still mounting the straps? I mean just glueing them on the inside of the backplate, through the slots and connected to the jet pack. Then it at least would look like the real setup
And the real jet pack at a bit of angle away from the wearer's head.