late to the game.....(been up in montana being mosquito bait)

for your consideration

1) Look at indyfabz set up, simple and elegant
2) Try doing a one day trip of the same distance you plan on averaging
3) after that look at all gear critically and see what you can cut

I guess a lot of "bike packing gear" like frame bags is geared for suspended bikes, see if you can avoid those (back to point 1)

have fun