Beau Bishop
I for one have been craving for chubby body mods for ages, but aside from something like Rattyhood (which isn't exactly a pretty item), I found absolutely nothing. Your best bet is simply combining baggy pieces of clothing well enough for it to seem like you're carrying a lil' something extra.
Also, a good hair item can help massively with adding the illusion of chubbiness to your avi.
I for one find it sad that all body mods seem to be about the same body type, but I don't doubt in the least they'll find a way to cash in ideas for people who want a heavier looking type of avi. </3
The Dylene legs are good for thicker thighs and calves, but they end in those tiny feet. Still, closest items I've found to my actual lower-half, so I deal when I use it, haha.