All “sumorgs” are for ladies ie the kallah is there by the men “the mens tish” they also have food and hot food no body gaurds stand outside the ladies room forbiding men to come in it is not per se mixed but by litvish or modern men the men seem to trickle into the smorg (by the ladies side) and that is y u think it is a mixed smorg
As far as mixed seating I personally was involved w sb that wanted no hall in boro park would accomidate and I think one is willi was they had to go out a little to get accomidated