We just got a 2014 233s this summer and have loved using it with the family.
I have read many threads on not mounting anything to the rear bumper, so I know that was not a viable solution for transporting my bikes. Secondly, I did not want to purchase a $500 roof rack for my car, so I used one of the many ideas from the forum.
Basically, I removed all of the cushions from the dinette, and purchase 4 Delta Bike Hitch Lockable Fork Mounts Delta Bike Hitch Lockable Fork Mount in Tree Fort Bikes Truck Bed Racks (cat268)
My first idea was to just use the current boards in the dinette and mount them to the wood. I found after mounting the first one, that the wood was too thin and it needed to be thicker to keep the bike stable. So, I replaced the wood in the dinette with 1/2" birch plywood, cut to size. This proved to be much more stable.
Basically alternated, placing one bike in, mounting the fork mount with 1/4" X 1" bolts and went onto the next. I was able to get 4 mounts installed, and when I flip the wood over the mounts nicely disappear into the storage area and the dinette cushions can be put back on for dinner.
Bike Fork Mounts: $76
None Really, just make sure you measure and place the mounts where seat support cross bars do not interfere when you flip them over.