I generally up the 29 with 100% fuel, the 40 500lbers and the 2x ammo. As soon as I spawn, I bring the flaps up then WEP down the runway until 2/3rds down before dropping 2 notches of flaps and pulling back gently. Once I am no longer struggling to stay airborne, I level off and build up speed then auto climb to alt. With my setup, of course, I must make sure I'm at a base with some alt and down hill towards my take off or I'm taking off over water. Upping with 50% though, you shouldn't have anywhere near the trouble I do using the same method. To play it safe though and make sure you are taking off over water or have some down hill for maneuvering room until you are sure you can do it at a base with flat land and trees.

Never take off going up even a slight hill to play it safe, unless you don't care about the perks (which most don't anyways

).