I did consider lambsquarter but the wild ones around my area are pretty lanky and probably wouldn't make a very strong support. Maybe if I found some vigorous ones though!
Wild lettuce is a great idea! I have it growing all over my yard. My only concern with using it is that it may cross pollinate with cultivated lettuce. Apparently this could lead to a reversion of wild traits. As much as I enjoy the extremely bitter wild lettuce, I'd prefer to keep the two separate.
Giant ragweed would make a good candidate
This is a good one too! I remember reading somewhere that the seeds were also eaten by certain tribes.
Giant ragweed reminds me of another good one:
Giant Goldenrod.
From these I also started thinking that the glorious and omnipresent
mullein might make a good stake too!
The next season i reinforced the standing dead basil
I've never heard of such massive basil!
Originally I was thinking about a single season where the trellis would grow alongside the trellisee but your ideas expanded that to a possible rotational trellising scheme that would allow a ton of flexibility. Grow the trellis the first year with a better suited polyculture and then the second year grow the trellisee up the dead plant with a different mix.