I am re-reading The Mystery of the Mayanup Poltergeist by Helen Hack, an account of an Australian poltergeist in the 1950s that had many witnesses- I would recommend the book to anyone interested in poltergeists.
I came across an interesting, if frustratingly brief, snippet on p26, referring to Sir Henry Wilcox:
"Sir Henry was a farmer in Bridgetown but during his service in the Middle East in the Second World War, he had witnessed poltergeist activity first-hand as stones fell inside a military tent."
So poltergeists do happen in tents, if this is to be believed (and I see no reason why not).