Here is the problem with Slime. When you apply slime you render any chance of using tire plugs. Yes, the slime will solve most of your smaller holes. But typically the majority of us run aftermarket tires which are much more durable than the stock tires (event ITP's...Just kidding). I have used over 5 plugs with a sidewall laceration. If I had used Slime, the plugs would have never held due to the natural lubricity of the Tire Slime.
My best advice to carry for trail side tire repair is to carry a good tire pump, plenty of tire plugs and tools, Keep in mind that your buddies may need plugs as well so treat your tire repair solutions as if you were in combat by making sure that you have enough for yourself. I was with a friend one day who blew his sidewall out. He had no solution for a repair. So in order o get back to base camp we had to use my plugs. It took all of them, and the next day I had a puncture. Guess what? I had no way to repair my puncture. So I had to trash my rim to get back to camp. You get the point.
Like 3TV said, I also think a tube would be tough to get installed on your rim in the event of failure. Not impossible though. If you needed better insurance, you may consider products like Tire Balls, or something similar. Back in the old days before Tire Balls were invented we used to use the rubber inflatable balls you could by at K-Mart and install in our 3 wheeler tires. This would keep us from getting a catastrophic flat and allow us to finish a race.
