Just a couple of comments, mostly repeating what others have said.
You absolutely must get a hard case, with proper mounting - like a Kolpin. They are only about $35 and well worth it. I'm even at the point where I think it's stupid to carry a gun on a 4 wheeler any other way.
Yes, there is a tendancy, with scoped rifles, for the scope to lodge against the case. First, I'll say that this has never been a problem for me, but I mostly use my Kolpin for boating, trucks and air travel, not 4 wheeling too much. But it gets tossed and bumped plenty. My scope has never gotten messed up ... yet.
ON THE OTHER HAND
, after several years of using the Kolpin, last fall I finally figured out the danger of the way my gun's scope set in it (DUH!!). I made a spacer for the end of the barrel out of a cushion-y blob of some tough rubber foam material I had in the garage, wrapped it up with duct tape so it would slide through the fuzzy lining into the case. The tape also toughened it so the barrel of the gun wouldn't pierce the foam. Also fastened a long string to it (running out of the case and taped where I could reach it) so I could pull the blob out when not needed.
By the way, the way my scoped rifle sits in the kolpin, I can put a box of 20 shells in the "butt end" of the case. Takes up just the right enough space to keep the rifle from sliding that way and also is a proper way to transport a box of shells on the airline (case locked after inspection, of course). No chance of getting there w/o the shells I want to use.
I find the Kolpin much handier than any other soft or hard case I have for every use - cars, boats, etc. It's as convenient as a soft case in terms of access to the gun and size, but as protective as a hard case.
Although it is not water proof when submerged, it will definitely protet the gun from getting soaked from splashes and rain in a boat.