Once the plane is over the ocean, very discreetly bring all of your gear into the toilet. You might need to make several trips to avoid drawing attention. Once your kit is in place, put a beaker containing the peroxide / acetone mixture into the ice water bath (Champagne bucket), and start adding the acid, drop by drop, while stirring constantly. Watch the reaction temperature carefully. The mixture will heat, and if it gets too hot, you'll end up with a weak explosive. In fact, if it gets really hot, you'll get a premature explosion possibly sufficient to kill you, but probably no one else.
After a few hours - assuming, by some miracle, that the fumes haven't overcome you or alerted passengers or the flight crew to your activities - you'll have a quantity of TATP with which to carry out your mission. Now all you need to do is dry it for an hour or two.
Food for thought. And what kind of anti-snake countermeasures do we have in place?