You should see all the stuff I take when I go to TN or Cuba..... tons of tools, spare parts, oil, computer,etc.....Just never know what you or another Spyder Ryder might need.
In Cuba the one thing I didn't bring along was new Y pipe gaskets(honda) I just got. I had put mine in and didn't feel the need to bring them along--- but low and behold they would have come in very handy as *someone* blew hers out in Cuba. Could have replaced hers in about 1/2 hour in the parking lot.
I keep my tools in my passenger seat bag so I can take them in the motels at night. Clothes go in BRP R35 cases, trunk is left for laptop, misc stuff. Topcase for raingear, extra helmet, etc.
Smaller bottles would work well if you're cramped for space. For short day rydes of a few hundred miles I don't usually have any extra fluids with me--- except H2O !