RE: How to effectively pump to plane?
I think you are on the right track here, but a couple of points stand out for me.
I'm not sure why you want to "push against the fin with your back foot very soon after you start to pump the sail".
It seems to me that in order to do a full body "all you've got" pumping sequence you are basically pushing the fin all the time, and especially as you pull back on the sail at the start of the pump. If you aren't "pushing the fin" then alot of your effort is going to be lost. Load the fin up as you start your pump.
Next, you suggest "after you initiate the sail pump with your front hand and just before you finish the pump with your back hand)".
Hmmmmm.... I always thought that I do these big pumps with both hands at the same time. It sounds like you are trying to include some sort of "flutter pump"( where you sheet the sail in and back at the same time) action in what's basically a full effort pump.
On a full body "all you've got" pump you bring the rig more straight back, the idea being to put as much force into pulling the rig back as you can so your weight comes off the board and at the same time the mast foot and feet "shoots" the board forward and up over of the water due to the "direction" of the force of your pumping action.
Maybe I'm wrong, here. I'll have to go out and see again what exactly it is that I do.
You are entirely correct, the timing and "rhythm" is critical to making any kind of pumping work for you.
Hope this helps,