My immediate thoughts are to concrete in two posts either side of the growing area, a wee bit in front of the tender walls and connect them with wired vine eyes, doubtless you have already thought of that and are looking for something else. The posts could of course be anything ie some sort of ballustrading or decorative finished timber or metal...maybe even a couple of decorative lamps like this.
When you have a solution...do make sure you come back with a photo of the job finished..I for one would like to see it.
Steve...