We (husband and I) are planning on a thru-bike in April 2019. We are really hoping to spend a night in the Grand Canyon but recognize there are some logistical issues in that (like shuttling our bikes). We have not decided whether we will try for an overnight or just a day, yet, but would like to know how difficult is it to acquire the overnight permit when you show up? I have read the AZTs page re: issuance at the office but am wondering if people are turned away? It sounds like it is issued to a "group"...what happens if more than one "group" shows up during the day? What do people do?