I don't like to leave bug guts on the painted parts for too long, nor on the windshield. Some guts will actually eat into the clearcoat if left there long enough. Windex makes some wipes that work well, but make sure to get the ones WITHOUT amonia. Packing for cool/cold weather riding is easier to me than hot weather...you've usually got your jacket/chaps/gloves on, so don't have to be concerned about storing them, and you don't sweat and get clothes stinky so they can be worn more than once, and if they're made out of the proper materials, can be rinsed out and worn again...wicking socks, underwear, etc. A good baselayer, a windproof, lightweight fleece jacket that can be worn underneath your regular jacket, and the rainsuit if it's really cold or of course, raining. Keep your neck warm...70% of your body heat is lost through the head and neck.
I'd lose the oil and the octane booster, but I'd take the tire plugger and some way of filling the tire with air...I have the CO2 cartridge thing from my mountain bike, but the small compressor would be better if it doesn't take up too much room.