Jumpsuits are not just casual garments anymore. Lately designers are making very dressy jumpsuits that belong in the category of evening wear just as much as dresses do. The neck styles, sleeves and legs as cut as elegantly as gowns are. For this reason, you should have no problem finding a jumpsuit that is appropriate for a night on the town, and that fits your body type very well.
Here are two examples that would look great at a fancy soiree, I think:
Plus-size evening jumpsuits pictured:
Left: A PLUS STYLE APPAREL A Plus Style Womens Jumpsuit with Jeweled Halter Neckline
Right: A PLUS STYLE APPAREL APS Collection Women’s Double Slit Jumpsuit -3x Flower Pink