flowerbug
Garden Master
...
In my gardens, I've only had one cowpea cross (between two yardlong beans) since 2005. Don't know if that is because cowpeas don't cross easily, or if it is because my Northern bees don't know what cowpeas are.
they needed some sweet tea!
Only one plant appeared crossed on the end of the row, and when I saved & planted only the seed from the opposite end, there was no further evidence of crossing. Take that as reassurance that your project is doable.
never hurts to try if that is all you have to work with.