OK I MIGHT have split squats dialed in. Been working on ankle and hip flexibility, added a bunch of stretching and warm ups before I start, and corrected my form to the point where I'm getting through sets smoothly now. It's HARD but I'm spending more effort on lifting than maintaining balance and compensating for flexibility.
Ankles still not perfect, there's something funky about my hip alignment, but making progress.
Also between the dumbbells and body weight I'm closing in on 300lbs total.