For that kind of trip you probably need either a trailer, or full set of bags, not both. Longer tours do not mean more gear, if anything the reverse can equally be true. Longer stages between available food and water, extremes of weather, total required self-sufficiency, etc... mean more gear. You might make 50 miles with all that stuff, and 80 miles with a more reasonable load.

I would google earth your trip to see what kind of terrain you are facing as you proceed.

Your gearing is too high. With a loaded bike you really don't use the top gears except for coasting at high speed which is just something some people love to do. Getting a 20 inch lower gear, and tightening up the steps is really inportant. You would probably make better speed under most circumstances with 18-90, and the tightest steps, least double shifts. There is a comon tendency to go for the widest tange which is normally a bad idea.

You can wear whatever you want but I would recomend the sewn in pads and no undies, and a Brooks seat, then you can probably forget about your seat for the rest of the trip.