RE: Hangar 9 33% Edge 540
My last motor mount measured only 7.25" from the motor box to the cowl opening. I needed 8" so I cut a 3/4" thick block of hardwood to mount just behind the plywood and extend my motor. I also changed to 1/4-20 t-nuts to fasten my three 1/4"x5" hex head bolts. Each bolts weighs 1.1oz for a total of 3.3oz. Perhaps a thinner bolt could be used here but I get the impression that there is no need to save weight this far forward.
I drilled holes in 5 sides of the mount box on the firewall for air flow into the battery and ESC area. The left photo also shows the built-in right thrust on the motor box. My PVC adapter and wood blocks follow the angle.
Note the perfect covering pattern match from the cowl to the fuselage. This is why I am a Hangar 9 fan!