@F3G:
I like the business opportunity you've proposed. I might just look into this BUT it would require some capital expenditure which I do not at the moment have.
However, I have pondered an alternative.
The evening before a flight, from henceforth, I am going to eat copious amounts of beans, burritos and eggs and drink the nastiest American beer I can find (Miller beer comes foremost to mind). Then, when an obese citizen of this planet sits next to me well, let the fireworks begin!!!!
I bet they ask to be moved to another seat!