Tri tip bison sous vide techniques. Preface:

I am cooking a private dinner for 14. Americana themed, surf and turf is what they asked for the main entree. I want to cook bison. The only cut I could find in town in time was a tri tip. $15 per lb. So $60 later, roughly 4 oz. per person. 

Requirements:

I want a perfect medium rare. 
Tender/melt in your mouth bites. 

My questions:

How do I obtain that maximum tenderness texture. 
How long do I sous vide for?
Is there a significant difference between beef and bison?

I have 24 hours to play with the protein. 
And I'm open to any suggestions.
Medium rare tri-tip can be achieved using a water bath at 130 - 135F (55-57C) for at least two hours and up to 7 hours.  You will probably not get "melt in your mouth bites", as bison tri-tip is a leaner cut, but it should be quite tender if it is sliced against the grain.