OK,
There are always some nuts who hauled enormous weights over vast distances. So what?
I think you first need to decide about the character of your trip:
On one end of the scale, there's the camping and cooking method, which means carrying more stuff, but also cheaper costs and more chances to experience nature (and meet people)
The other end of the scale is the luxury one - sleeping in hotels/ motels and eating in restaurants. Your bike will be significantly lighter in this option.
But, even if you choose the first option, I see no reason for carrying more than 55-65lbs. In this weight budget you can include enough spare clothes, camping gear, cooking gear, tools, tablet PC, etc.
The less you carry, the more milage you'll cover every day. A heavy load will reduce your daily milage, and force you to do more rest days due to fatigue. Packing every morning will also be a noisense, with too much stuff.
More remarks:
1. within the continental US, you don't need lots of spare parts. It's not necessary, for example, to carry a spare derailluer or a spare tire (which are heavy and bulky)
2. Trailer can enable you to carry more, but for the ~60lbs load I mentioned, are not a must.