I find that--more than just covering the distance--my training is a series of trial-&-error experiments that I do on myself. The longer the race, the more things there are to figure out: pacing, nutrition, clothes (chafing!), etc. These training runs are where I figure out what works for me: how fast can I go, how/when/what can I eat to refuel, how hot/cold do I get...hope I'm not making it too complicated!
Because of all that, treadmill doesn't do much for me except to keep fit. The conditions don't match closely enough for me to use the information from the run to figure out "what works". I think this is why Coach Nancy and others are suggesting that you do at least some of your runs outdoors.
Anyway, your plan looks great so enjoy your training and have fun at your race!
A ship in the harbor is safe. But that's not what ships are built for.