Wow wapiti, that's an awesome idea and a massive undertaking.
I tend to agree with Pappy that from scratch, a split log to bow is 3 days would be difficult to pull off with osage. Rings would have to be chase. I never been fortunate to work with a "straight" piece of osage. All that I've worked with have had to be heat corrected in someway, usually in several session to remove twists, humps, even up limb r/d... I suppose if all of that was done prior to the event and the staves were near floor tiller stage (which they would need to be to do the heat corrections anyhow) it might be possible.
Pappy and Twin Oaks pull off a bow building clinic a couple times a year for the Boy Scouts. But, have you seen the facilities at Twin Oaks? Something like 8 to 10 vices and probably a few more work stages than that, bandsaws, belt sander, scrapers and rasps galore.
Now, that I've thrown a wet blanket on your plans, if I can help let me know.