How fat are we talking?
I've dated some fatties that in the right clothes were sexy as shit. Tits all pushed up and plump thanks to a push up bra. Legs and ass looking smooth and round and tight thanks to black spandex, but, but, but when they take off the clothes, tits sank like the titanic, cottage cheese galore in the ass and thighs, the roundness turned into a mound of pizza dough and that smell. That scent of dried pussy sweat between those fat thighs festering all day long.
Big girls don't scare me. And I could care less what people think of me for being with a big girl. When I was 22, I did. But a decade later, I literally couldn't give a shit what people thought.
Your post above does bring up my major phobia though. That smell issue is a big old non-starter. Especially smell. I expect her to smell absolutely clean and flower-like at all times. Skinny or big.
Her body can droop a bit...that doesn't matter too much. All women droop with age, more or less. But smell...if it's rank, that's just not going to work. I would walk. I've very particular about grooming and smell, and expect the same.