Unless you are planning to spend a lot of time and explore the areas really well as you travel, you have way too many clothes.
Your full time job on this trip will be to ride 6-8 hours per day. You are going to be filthy within 1/2 hour of leaving every morning. You are going to be tired and filthy when you get done in the afternoon. Once you get out of Mississippi no one will look twice at you when you walk into their restaurant covered in dust wearing unbuckled MX boots and jogging shorts.
I carry one pair of socks, one jersy and one pair underwear per day and I change those every day because it makes me feel clean. The guys that were on the last trip didn't change anything in the first 5 days.
You need one pair of pants for the trip don't bother trying to wash them on the road. I like the kind that you can zip off the leg bottoms. I carry a pair of lightweight shorts for hanging around or going to campsite wash rooms.
You aren't going to be playing basketball, you won't need the tennis shoes. I bring a pair of flip flops to wear around camp or to a restaurant if we go somewhere.
The weather changes a lot during the day, it will start and end cold and be hot in the middle. You aren't going to want to stop and dig through bags to pull out the perfect clothes.
You need a riding jacket that you can take off if it is too hot, put on when it isn't and put a liner in for the mornings or when crossing the passes.
Two pair of gloves is plenty.
The typical breakfast is granola and jerky. You will be stopping at gas stations every 3 hours. You can clean up there and get water (fill your camel back out of the soda dispenser don't buy bottled water) and it is really hard to pass up eating lunch at these establishments that sell hot food. You only need enough cooking stuff to heat up a can at night. I do like to percolate coffee in the morning.
If you are doing the whole three weeks, the weather will eventually force you into a motel. Go ahead and budget for a couple of nights. It will be a luxury that you will appreciate plus you'll get a chance to spread all your shit out, wash it and wish you hadn't brought so much.
You can't bring enough tools.
The hand pump is all you need in that department. Do you have practice dealing with those mouses? Check your wheel bearings before you leave.