Er....no, not quite
Putting a bit of board under the centre stand just means that you have to lift/lever the weight of the whole bike further up to go over the apex of the arc.....putting a big board under so that both wheels AND the centre stand are on it returns you to the exact same place as you started off at
Just get TWO bits of board, or ONE double thickness for the back, then ride the bike over the board so they are under both wheels (or so that the back wheel is over the double thickness bit) and the centre stand will go down on the ground inbetween the boards
Then try the normal procedure.....the bike will have already been 'lifted' by the thickness of the boards so the apex of the arc will be correspondingly lower.
If you have had a bad back and a fully laden bike, go for the ONE board under the BACK option, as it will mean the seat height isn't that much higher, so getting on and off will be easier. You will still gain the advantage that raising the rear gives to your effort, and you dont have to worry about positioning two boards accurately...simply ride over it until the back wheel is on it.
Simples