Two weeks. I was housesitting for a friend. Very private with a pool and hot tub in the backyard and a jacuzzi in the house. I stocked up on groceries.
Last winter my wife and I rented a secluded beach house with a pool on St.Croix for 8 weeks. Were naked always except for trips to and from the airport to pick up friends and one grocery pick up when we first got there. Otherwise, we had things delivered.
Idiomatically speaking, two days. It wasn't a full 48 hours. But definitely slept nude. Stayed nude the whole day and night. Slept nude again, then didn't get dressed until a little past noon.
1). Visiting a nudist resort with my family when I was a teenager. Eight full days. The weather was perfect, so I wore nothing at all for the whole time; I even slept on top of the bed covers. 2). Housesitting for friends of my parents on spring break during eighth grade. The house was quite secluded and private, and I stayed nude the whole six days.