When I lived in San Antonio, I had a neighbor who planted okra next to giant sunflowers and he saved the seeds from the okra for the next years planting. The okra grew about 15 feet tall. Has anyone experimented with such a cross polination?
These plants are not in the same family, not possible to cross pollinate.
There are Okra that grow to 15 feet such as the old variety from Louisiana and Texas with the nick name of Longhorn or long hook. For me they also stretched out that far but I only grew they about 3 feet apart and let them grow branches that reached past each other without any lose of fruit. I grew about 90 plants in 120 feet and all were very healthy and productive. Of course their "trunks" were up to 4 inches across.