Is it permissible to hold a mixed wedding reception, where men are seated on one side and women on another side far from them, with the possibility of each party seeing the other from a distance, when it is impossible to hold two separate receptions?

If men and women are in completely separate areas, with different entrances as far apart as possible, then there is no harm in holding the wedding in one place, provided that one is keen on lowering the gaze and that women adhere to the legal hijab and modesty.