Yeah Kid, it's not really that massive, it "Y's" into (2)-10"+/- diameter branches at about 10' up, above the hollow trunk part. I did consider dropping these upper "small Y's" first and then cutting the remaining "rather harmless" trunk later; but how to cut these branches that are 10' up? -Option 1) build/get some staging to stand on to get up to 10' -but who goes through that trouble? 2) Cut them off from a ladder with a helper pulling rope (this seems like bad idea as branch can take out ladder & you're standing on it w/ only 2 points of contact (feet) with two hands on the saw that's at head level, and you never cut at the right non-pinch angle - been there-done that (don't ask!) ), or 3) Put on my climbing spikes w/ a helper pulling rope (better than a ladder, but you still can't run away!)
Hmmm: I wonder if 4th option would use a "mortise & tenon" to stand on. - I'm sure there's a better official name: i.e. saw a mortise hole about 5' up and stick a 2" x 6"(or 8") wide plank in it to stand on. That way one could still jump and run if needed? I guess I need to check if the lower hollow part is wide enough to allow a deep enough "mortise" cut to do this. If not, alternative could be to drill (2) 1" holes about 6" apart and stick in a couple of rebars to stand on?