It might not be, I'm not sure. Almost certainly not for long periods of time. There's just two components which I don't have something off the top of my head, but I have ideas for.
Keeping the critter bent forwards, and counterweighting, if necessary.
The first component, I'm thinking of either tying a rope from the chest to just above the knees, with the length setting just how forward bent they need to be. (In the extreme, tying the thighs to the torso, just leaving the lower legs free to move)
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Keeping the critter bent forwards, and counterweighting, if necessary.
Not the most elegant, but feels plausible.
I can @ you on mastodon so you can see it if you want, but won't DM it, if that works for you?