You cant have gsnp thru resevations more tahn a month in advance unless you are a Apilacion trail thru hiker. Even then not tru! All shelters in gsnp are only reservable a monthe in advance. two bunks in each shelter are held for thru hikers. If shelter fills with researved hikers and more than two thru hikers are present . The thru hikers can set a tent outside shelter. Only a thru hiker can tent in gsnp Legal! I would not go without tent. If thru hikers or others lie and fail to produce permit on inspection,even though you are tenting illegal outside the ticket goes to them.! Happy trails