For those of you still over 300 lbs - what do you do when

I would suggest that instead of buying two tickets to instead just purchase one ticket and get an upgrade to first class.

The seats will be larger, the seat belts are usually longer, and there will be more room in-between seats encase of 'overflow'. Plus, the food options are often healthier...and you get to load the plane earlier, don't have to worry about finding overhead compartment space, your coat will be hung in the closet, and you get to drink while the rest of the plane is loading....

When I weighted 322 lbs. I would always half to ask for a seat belt extension if I sat in coach and only very occasionally needed one in first class.

Lol, and for all the money you get a FREE set of headphones so you can watch the movies!!