Obviously, my training is over. I'm resting and drinking water and stretching. What else can I do to be totally prepared for it mentally, physically, and emotionally?

I like to warm up the day before, some people do nothing. I like to go through my normal warm up routine including a few strides.

Eat complex carbohydrates, but do not stuff yourself. I try to stay with something light that I know will not be on my stomach and I will not be belching in the morning.

Visualize the race, think about having a good swim, fast transition, easy bike, and run.

You have done the necessary training so picture yourself setting a pr.

Try a 1/2 hour cruise on you bike. No efforts just a medium slow ride. It'll help keep you loose and focused. Pro cyclists always ride on days off even in long multi-stage races.

if winning is your goal, picture yourself winning. visulize every part of the race ahead.
If your goal is to finish, picture that

if you believe any of this you arent ready, but good luck anyway. in fact, kick butt and have fun.