When you purchase the Rhino in BOABO, is it possible to park this anywhere and save?
I've tried taking it to a couple of hideouts, but it says something along the lines of 'this is too big to park here'.
No, there is no way to save it. I believe some large vehicles can be saved using the "chevron bypass method," but even that won't work for the Rhino.
I think you can save it by leaving it outside your apartment and saving the game.