+ 1 for the Big Agnes. I now bring mine on trips where otherwise I'd be sleeping on a couch or pullout, even with a car or plane trip, because it's more comfortable than bad beds and really packable. Might be out of your price range, but definitely best value for the dollar. Otherwise I'd say definitely look to borrow or rent. I wouldn't go without something - important for comfort, keeping your bag away from dirt/dew, etc.
Sit bones = ~135 mm, saddles that work ~ 155cm/6.1 in wide
2003 da Vinci (custom road/all-rounder)/Terry Butterfly Ti
1994 Gary Fisher Nirvana (vintage MTB/commuter)/Terry Butterfly Chromoly
1991 Terry Symmetry (NOS frame/fork, project in progress)
1973 Raleigh Super Course (project in progress)