You can t solve you re problems with the same level of thinking that created the problems.
Mounting a garage door opener off center.
Use one piece as near to the top as you.
Offset garage door opener guests.
You may need to duplicate this for an off center mount.
Bolt the angle irons to a rafter or rafters with lag screws.
That means the garage door opener won t work if it is placed in the center of the door.
As you said run perforated angle iron from the center stile to the next stile over.
If your door has extension springs the opener must be installed in the center of the door.
Some of the door openers especially commercial brands mount along side of the door on the wall and may work if you can find one that is cost effective.
Overhead opener drive types.
Attach the straps to the irons with hex head screws.
Most units hang from angle irons and metal straps that have holes drilled in them at regular intervals.
Go ahead and mount it off center and save yourself a headache.
The opener can be installed within 4 feet to the left or right of the door center if there is a torsion spring or center bearing plate in the way of the header bracket or door bracket area.
Can an opener be offset from the center maybe a couple of feet.
If the door is properly balanced you should be able to locate the operator anywhere but always perpendicular to the door.
You can be off center with the opener provided the door has a torsion spring which it sounds like yours does if your door was extension spring the kind when the spring stretch along the horizontal track then it wouldn t work properly.
Attach the straps to the power unit with the hardware provided.
Genie chaindrive 550 garage door opener heavy duty chain drive system includes 2 3 button remotes wall console wireless keypad safe t beams model 2035 tkv black 4 6 out of 5 stars 501 133 30 133.