Im a little confused by all this discussion.
The blue line will give you the most efficient single engine Climb provided you havent modified your aircraft heavily - its been tested to exhaustion by the manufacturer.
If you cant reach the blue line on one engine at your present angle of attack, flatten your climb until you can reach it, and then increase climb to maintain. Do not turn or even breathe before youve reached it. If you have to flatten your climb until you're level to just make the blue line - that is bad.
If you cant reach the blue line even in level flight - that is worse: youre going down; find a good place so as not to bend her too much.
Thats about all there is to it.
regards, OORW