There's a small bed in the corner of my landscaping. It's separated from the landscaping coming down the side of the house by a stone drain for the downspout. Behind it is the back porch and it's edged by grass on two sides. I want something in the corner of the bed. Currently there are three English lavender along the curve of the two open sides with a red double knockout rose at the center of the curve. There's a catnip in the center of the bed and catmint filling in around it. The corner closest to the house has orange canna. I want something on the other corner that's out against the yard. I'd like it to be in the five to ten foot range with a spread of no more than three feet. A little taller would be better because I want it to provide some color above the lavender and rose as well as a little privacy for the porch. Along the back of the porch are orange rocket barberries so the plant would be a transition between the barberries and lavender. I'm not overly particular about the color but yellow or orange would stand out from all the purple or red would match the rose. A dwarf tree would be great there but I'm concerned about how close it would be to the concrete porch. My best idea right now is a to put a trellis there with a clematis, there's already a sturdy upright that I could connect it to. I would really like something with a longer bloom season though. It's full sun, zone 6b, with rocky clay soil.
Prairie Moon has two Living Fence collections. I would select one of those. These super tall plants are similar to sunflower where is a single stem. I would look at one of those plants or plant sunflower. The edible sunflower are beautiful and would fit your needs but are annuals. There are native perennial sunflowers as well.
That's an interesting collection. I think I've previously looked at three of the six. I'll give them another look. If I had the space for it I'd love to do a naturalized patch like they describe. I've also looked at sunflowers but, like you say, they are annuals and it's a pretty windy spot and they're vulnerable to wind damage. I've seriously considered false sunflowers I'm just concerned that they wouldn't get as tall as I'd like.
I have some false sunflowers in my hell strip by my ally. It gets pretty tall around 6 ft but not as tall as some of the living fences.
You could do the perennial sunflowers. I think the Maximilian Sunflower is recommended because it's doesn't spread as much. But I don't have one