If the tree had big fat branches to hang a bag from, or put a screw eye into, the ts probably would have taken note of it before coming up with this nifty diagram concept.
When i roped mine between two trees they were big pines with small branches very high up. Though, I must say in defense of those posters suggesting the branch concept......the ts did draw a couple fucked up trees with some pretty strange branches. Then again, your guy is throwing a kick and a punch at the same time. I am not sure this project should be left in your hands any longer. Go buy a bag stand.