I agree with the idea of making a swath of grass/path following your existing shapes, and gardening the rest of the space. I also agree with a brick or stone edging. Both those things worked very well for me. I don't have a sidewalk on the outer edge; my constraint is a deep ditch, which forms the outer limit of the garden space. I like the relatively straight line it makes as the edge. You don't have to do it all at once - start with Yard Advisor's corner bed. Get that set up and planted and keep thinking about the rest. Over the following year - or two or three..., you can gradually extend the corner bed towards the house bed, and along the sidewalk. If you do it gradually, it won't feel like such a big change/lot of work but rather like a natural evolution for the space. That's the way I did mine. Initially, I created a big bed in front and a narrow one along the driveway. A couple of years later, a small one was added behind the driveway border where the driveway curves plus another small bed was added in the N&E corner of the property. After a couple of years it was clear that all of those needed to be made more coherent and connected. So I measured a consistent distance from the edge of the main, large bed to eastablish the ribbon of grassy path that ties it all together. The ditch limited the outer ('moat') bed to a very narrow shape but the brick edge gives it more definition and it all works quite well I think. I think something similar would work well for you as shown in Yard Advisors drawing. Here is a link that might be useful:

Tagetes lemmonii doesn't get 8' tall. I've had several of them, and even in great soil it doesn't get much over 6'. Oleander will do it, as will yellow cestrum (the original, not the hybrid colors which are much shorter). Yellow cestrum is limited in distribution, as far as I know only East Bay Nursery in Berkeley was rooting some of it. Grows like a week, totally xeric once established, pest-free, not as bushy as oleander though. The original yellow cestrum rootstock came from my gardener's backyard, which is how I ended up with three of them in my yard! It hasn't been sold commercially for over 50 yrs until EBNursery started rooting some. The two have different shapes: oleander is more classic bush shape, thicker at the bottom than at the top. Cestrum has tall, slender multiple branches; less fully leafed and they tend to arch outwards, growing more vase-shaped.

I am in SW WA and have a similar problem. We're on a hill and have woods around us, except the SW exposure of the house. It gets 3-4 hours of hot afternoon sun. We have white stone siding and the whole area gets exceedingly warm. Many things I've tried there wilt in the pm, and/or just don't do well. The best perennial I've found is something that was tagged "Texas Sage" and it's one of those greggii sages. Loves it there. One cultivar, Hot Lips, is really happy - I bought a whole mess of them. Another plant that does well, surprisingly, is fleabane. It's low growing habit probably keeps it cool. And of course, there's always Walker's Low Nepeta. I know these aren't climbing, but they might help someone. I myself am heading out first thing tomorrow for some clematis and some of Zoomermom's suggestions.

I don't pay too much attention to pure yellows in the garden, and I hardly ever photograph them unless they're gigantic or have an amazing edge. But I do use them to separate the colors I like in the garden. LOL They seem necessary, but they don't get my love and devotion like the pinks and purples. Most of your yellows, however, are not plain. They have eyes or edges that make them not just another yellow. My favorites of these are Alexandra Paige and the Princess Diana X Green Illusion crosses. Those make me sit up and take notice. Debra