Hi.. hard to recommend without knowing much about the bride's family, and if you want to have music and dancing, or just a nice, noisy meal. Since the group is small, one option is to find a nice Chifa with a large, separate room for your guests. That way you control the food expense by preordering, and can negotiate a corkage fee if you'd like to bring in some wine.
By the way, you can also arrange with the Surco Municipality to have champagne served after the civil ceremony, and you can usually hang out for half an hour or so.
"Hay que distanciarnos hoy para luego abrazarnos más fuerte".
-Guiseppe Conte, primer ministro italiano.