I would start out by asking the daughter about the bed. Does it have a footboard (so less overhang at the feet is necessary), does she want a pillow tuck, how thick are the mattress and box springs, and does she want the quilt to cover them? I understand the desire to finish this in time for the wedding, but the new couple would probably be happier to receive a quilt that's appropriately sized but delivered after the wedding. You might even have time to make another top that doesn't require such large borders, and you could enjoy the process of making the quilt instead of feeling flustered and pressed for time.