I scraped/found a absolute amazing dataset of a singular Posey/canvas straitjacket outfit with consistent pose and bondage by like 15 different people, trained it, then forgot about it for like, 6 months.

Welcome to the Sophorium "Why the fuck did I think this didn't work" collection. Boy do I have a lot of those...

Because it's illustrious, I'm sure you can do whatever you want with it, but as the concept is trained: works well two ways, and pretty well a third:

Str 0.8 to 1 (1 will work better with the thigh>ankle connections)
lying on back, straitjacket, thigh straps, arms crossed, feet together, knees apart, bound ankles

Or

lying on back, straitjacket, thigh straps, arms behind back, feet together, knees apart, bound ankles

Lastly, as a suspension

((suspension, restrained from ceiling, bondage)), bound ankles, from below, thigh straps, arms behind back, feet together, knees apart

I think this had a ring gag, best prompt is ring gag, teeth, tongue