What she said over all. I feel your pain. I'm a short, sturdy cyclist. Even if/when clothes are shown with plus sized models I'm so short I still can't envision if it will fit. Shorts fit me like capris, capris go over my feet ... arm skins cover my fingers.
Waaaaaaay back in the day I worked in design there was a saying in the industry "Show everything or show nothing". For example I was once working on promo material for a film festival that wanted to show a crowd. Do we have plus sized, tall, short, skinny, each with examples of different races, hair styles, colors, some disabled, varieties of disabilities etc .... wrap the graphic around a bus to fit them all in or do an abstraction of the crowd concept.
We chose the abstraction. Less production cost. ;)
But I do see the need for this. For bike culture to grow folks need to know you don't have to be skinny to ride. You don't have to get suited up in lycra to ride. If you're not skinny but want lycra anyway you can do it an look fit, fast and fabulous! You can ride in a skirt or anything you wish and be fit, fast, fabulous and comfortable.
Even the writer of www.velovogue.com who I like a lot tends to feature skinnier folk so ... I see the need for a blog! One that writes about struggles with and solutions to riding and looking fabulous at any size shape and style.
Go for it!