So, we recently had a discussion here on Iain's forum about the practice of uke-waza, and I had mentioned that I'd been working on an article looking at that very topic. Specifically, I was writing about what I see as a "modern tradition" of practicing uke-waza with your opponent directly in front of you, and how to transition from solo uke-waza practice to partnered practice in a more practical manner. I have some drills that I like for this purpose, which you can see in this article
They are still very basic, and work the "block," or "deflection," aspect of the waza in isolation--no open hands, no grabs, no strikes, etc. Just the basic movement as a "block," or "deflection." That said, these drills are very easy to open up into kata applications! Certainly much easier than the "standard" back-and-forth, head-on blocking drills.