I am just not sure that the "stakes" could be sufficient enough strength to create the ballast effect you are looking for. I suppose you could use those big party tent stakes that they hammer into the ground, but that would not exactly be easily portable and quick to setup. Keep in mind in your thinking to not only consider your static weight, but when you are in your hammock and move- creating any bouncing...this movement is a force multiplier that dramatically increases the demands on your stand. This addresses inward force and there will be side ward force occasionally when you swing horizontally in the breeze. I do like your Sketchup drawings..a mind in action!
"The music business is a cruel and shallow money trench,a long plastic hallway where thieves and pimps run free,and good men die like dogs.There's also a negative side"
Hunter S. Thompson