Dejoha, it occurred to me early this morning that there is another way for you to erect your stand. Since you are using 3' rebar stakes, why not put them right at the 2x4, at the same angle, and lash the board to the stake? Then, instead of guying the tops out, run the guys to the adjacent stakes and lash them to both the board and the stake. I believe the 60* angle will enable the opposite board to prevent tipping when one person gets in a hammock.