My wife and I did a 7.5 week trip (on our first Spyder, a 2008 SE5, equipped with 2 GIVI bags) around the US and Nova Scotia, New Brunswick and Ontario (San Diego to Florida, up the east coast to Cape Cod, more east to Canada, started going west to Seattle and then home). We packed each one extra top (T-shirts) one pair of socks, shower clogs, one laptop (in carry case), razor, deodorant, etc. All our stuff for the saddle bags was packed in 2 pillow cases, one for each bag. Keep your body clean and wear a clean shirt each day...no one will know how long you have worn your pants. Wash the T-shirts at night in the motel sink, along with your socks. Or if you rather, most motels have washer/dryer. You are a motorcycle (Spyder) rider, not a cager. The people you will see while traveling will never see you again, so don't worry about them. The Spyder riders you will meet don't care about anything except your friendship and comrade. Worry less, live longer.
We also each had a leather jacket, windstopper and FroggTogg rain suit.