Ok i did some more testing
I tried using my own Urara to see if i was able to fuck myself over on stamina.

My Taishin got rushed and had no Sleeping Lion proc
She won the race at full speed against my Gold Ship
Here's the race: https://streamable.com/bjws6g

My takeaway is. If the Taishin is good enough. Urara does nothing
If the Taishin is shit. You will probably kill her. (most people will have a shit Taishin unless they are highrollers or whales, but they will have a Goldship anyways)

So do as you wish with this info.