Back when I lived in goat-head country, I had heavy-duty tubes, AND the fore-runner to Slime. It was a bit like using suspenders and a belt, but it worked for me. I was mostly flatless during those (commuting to college) years, too.

I'll put in a plug for heavy-duty tubes. They are heavy, so you aren't going to win any races on them, but if your tire gets a big gash and the tube peeks through, it's not a crisis. DH ran for WEEKS before I got him to change out that gashed tire. (He's not real big on preventive maintenance) The tube is still going strong, thank you all the same.