Anyone having success using Drexler bros sit down start with a inflatable wing? YT link below if yr not familiar.
Angle of pull def better suited to parawing, but I've still not made peace with kneeling starts on a floaty board in ocean conditions. Can do it consistently, but after a lifetime of surfing, and wavesailing tiny boards, i just hate this kneeling thing, and my lower back doesnt enjoy it either, no matter how many variations i try.
Being in boardshorts doesnt help, had to ditch deck grip altogether, and now have nice board bumps like a 1960s log rider

It looks to me that this technique requires a free hand for the assist from sitting to standing and the one hand full power pull on the PW facilitates that. I don't think you can go straight from sitting to standing with no hands on the wing(you need the speed for stability and an inflatable requires both hands for power).

I would say this technique requires more athleticism than a start with knees as an intermediary. What about being on your knees bothers you? Pretty much every good wing start requires knee to standing. Most of the variation is on how to get to your knees with starts like the stink bug, giving you the ability to skip sitting to knees and start straightening your knees.

my recommendation would be to dial up the athleticism with some workouts focused on exactly what you want to do. Deep squats with your heels to your butt, switch lunges, burpees. Work on exercises that incorporate the stand in motion you want to accomplish and balance.

Try the one knee hybrid....front foot on the deck and back on the knee.
Starting on both knees makes me feel like a Gumby crawling up.