There is not much you can do yourself with these big heavy tires if you get a flat, unless you are capable of breaking down the tire and putting a patch it in (for a small puncture), or installing a spare tire your carrying with you. I have a repair kit I carry in my car that uses a "push-in plug" (for nail-like punctures) - but these types of plug kits are not really recommended by the tire manufacturers (they want you to break down the tire and inspect the inside and use a patch on the inside).
I thought about carrying a spare (there is a nice tire carrier available that fits on your trailer hitch with fold down loading/unloading ramps) and then you still need a jack, safety stands, and breaker bar and/or torque wrench to change the tire. I have the tools but after discussions with others, it seems the likelihood of getting a flat is really pretty low and hard to justify the cost of buying and carrying a spare.
If the leak is small enough you may be able to just air the tire up (monitor it with your TPS) and keep filling it up until you reach a repair shop.
Lastly, and probably the best option, is to have Roadside Assistance coverage where someone will come out and change/repair your tire on the side of the road.