I plant with a pair of tweezers which are about 20cm long so they add to my arm length, my tank is 50cm tall and the top of it is 130cm off the ground, I manage okay, quite easily actually and I'm 5'6"
Another thing to concider about a deep planted tank is light, as it weakens the deeper you go.
Holly crap! 6x54w T5 HO would probably boil the water at the surface!