Tried this. This does allow you to get the tk at a lower height easily, but unfortunately it negates the dash momentum needed for the combo since you're jumping backwards, so you end up too far to land the 5K (unless I'm doing something wrong). Thanks for the suggestion though.
That said, I figured out how to do it. There's actually a bit of leeway to doing this combo, and I was originally just trying to do all the inputs within one motion. You can actually just do 5S RC > 6[6]~ (buffer this and start holding during the RC animation) > 923S.