Well if all of the US theme parks are painfully aware of how obese many of their customers are to the point where they have placed a "sample" seat and gently ask people to "try it out for size" so that they can actually go on the ride, perhaps the airlines can take a lesson here with "sizing" the lavatories for passengers who are too tall or round to fit-at least that way those passengers can utilize the real bathrooms before boarding.
Please do not get me started on suggesting they also do that with the airline seats too! We all know how badly that will go!