Have you tried Rose of Sharon, DoV? I had heavy clay soil and they tolerated it really well. They have very sturdy stalks, too. They remind me a lot of hollyhocks. I like the idea of the beabalm, that and dusty miller are some of my favorite filler plants.
I have not. I will give it a go this year. Thanks for the suggestion.
I can fully attest that Rose of Sharon grows well in clay soils. One of the things to think about ahead of time is whether you want a tall column shape or if you want the bush to spread. If you want the column shape you need do nothing, but if you want it to spread you will need to trim the top each year - I basically just trimmed it even, and it will grow fuller instead of taller.