That looks good,
You are going to need some sort of lightweight bondo type material, like evercoat (catalyzed polyester filler) or some epoxy, I use this:
SUPER FIL from Aircraft Spruce
That Tamiya putty is probably lacquer based, it will be difficult to lay enough of it down for what you will be doing (shrinking, drying, etc.) It is good for pinholes or really small dings but the big stuff you need something that wont shrink. In my opinion