Please correct me if I am wrong, but if using a wing with just the cam bands, there really isn't a way to adjust the placement on the plate since it is strung through the plate itself (unless there are multiple slots on the wing to thread cambands).
Look at how long the slots are on VDH wings, for example:
Store | Vintage Double Hose
(note also 2 holes on each side.)
Here's DiveRite: Dive Rite Travel EXP Wing {25 lb | 11.3 kg} Lift | Dive Gear Express® and DGX wing has very similar very long slot w/ only one 1" cross-brace strip: DGX Singles Wing - 30lb lift | Dive Gear Express®