I completed everything under 10 so now I just try to get the last maps in 11 & 12 that I don't have. I don't mind playing the missions in 11 over and over again because they spawn the advanced secret garden, so it's basically the same thing as 12-3 except I won't get ampys. I finished 11-1 this morning, I feel your pain it's a horrible map, but 10-5 took me even longer.

Edit: And I only will attempt missions if I have atleast 80 spare stamina after completing it to be able to do the secret garden if it spawns.