I've never grown edamame or cow peas. I have a few questions.

First, are all the cowpeas bush varieties or are there some pole types? Are they as heat resistant as Limas and yard longs?

Can cowpeas and/or soybeans produce in a spot with only 4 hours of sunlight a day? In AZ desert?

Which is better in clay? I have a new garden area and need to loosen up the caliche before the winter garden is planted. I will be adding some composted manure but it will still be pretty hard caliche to start. I can't dig more than about 4" deep. Soil is alkaline, I do add sulfer but it only does so much. It does get pretty nice after a couple of years of compost and mulch but it's a challenge starting out.

Or, would I be better off with some sort of Lima bean in this spot? Or yard longs? Any recommendations?