Had a F/A at a previous airline who was a tad bit wider than the aisles, I always wondered about her ability to perform her duties in an emergency. As for the OP, I am pretty sure the extension (s) will work. SWA in the united states started charging for two seats if a person could not fit in one, I do believe though that if you can make it through the entry door, the airline can accommodate the seat belt situation.