What can I do if I get a flat out on the road?
Don't panic. This is not the end of the world. There are plug kits that allow you to patch your tire without removing it from the rim, such as the Stop & Go Pocket Plugger, available at Aerostich and other places. What's notable about this kit is that it doesn't use "sticky strings," but rather "mushrooms." The mushroom type plugs are supposed to work better, although they're harder to find. Don't get the regular Stop-n-Go kit, make sure it's the Pocket kit. The non-Pocket one is huge, and isn't really sized for motorcycle use.
It has been suggested to carry the Stop & Go, with its mushroom plugs, and also some additional tar rope plugs (sticky strings) which you should be able to get at your local Clueless Auto Supply. The reason is that tire punctures are different every time. The design of the Stop & GO mushrooms is better than the tar rope plugs, but they don't work for all punctures.
The Stop & Go is best used for simple punctures, such as a nail or screw through the tread. If you have an irregular or larger puncture, then the Stop & Go will not stay in place. The tar rope plugs are more likely to hold in this scenario. Riding for a long time on a plugged irregularly-shaped puncture is probably not in your best interests.
Stop & Go mushroom plug on outside and inside of a tire.
One good tip: since you need to trim the end of the plug sticking out of the tire off, to ensure you have something to do so with, use a piece of duct tape to secure a razor blade (like for a utility knife) under your seat somewhere. The Pocket Plugger kit comes with one.
Portable air compressors
Once you have the tire plugged, you'll need to get some air back into it. The best option for inflation, for many people, is to get a compact 12 volt air compressor. This will probably take up less space than CO2 cartridges, and you don't have to worry about running out of cartridges this way. Here are some options:
Some people prefer to use a thin bicycle frame pump instead, if for no other reason than to save the battery while inflating a tire in the middle of who-knows-where. If you decide to go this route, make sure you get one that's high-volume. It's gonna take a while if you need to go from zero to 35 psi anyway. The one in the picture below is from Planet Bike and will go from 30 to 36 psi in about 30 strokes.
Here are some ideas for storage options for your tire inflation items. To get to the pump you'd have to take off the side fairing, but it's only one bolt, and if you change it to an allen that's not too difficult.
You can use CO2 inflators with the Ultraflate Tire Inflator, also available from Aerostich or your local bicycle shop. Don't buy the company's CO2 cartridges; go to a sporting goods store and get the cheap ones.
Be aware that it takes quite a few CO2 cartridges to get a tire back up to pressure; many people only carry a couple, which is not enough. Here's a calculator that will tell you how many cartridges you need to have to properly inflate your tire (note: a 130/90-16 takes five cartridges to get to 29psi; six to 35.)