Hi Debbie.
Yeah, cool! Exactly that kind of side-brace, to hold the uprights apart even after the plant gets heavy and bears down on the strings.
Great creativity! Do you think you might make a second circle, if the plant gets lots bigger?
Like a "super-circumferential highway"?
I know there are meticulous, well-equipped wood workers who would drill holes in the uprights and turn the branches on a lath, then glue the branches into the holes like pegs. Like, for oak furniture, not so much for tomato cages.
P.S. this is what I meant by Boy Scout lashing:
