A fire extinguisher is CHEAP insurance. You never need one until you do, then is a bad time to realize that.
This actually happened to me. A was about 18 at the time and I picked one up somewhere. It was in the back of my car. My buddy had a ford Montego that burned as much oil as it did gasoline. He was adding his typical quart and it spilled....hit its flash point and started burning. You can't blow out a fire like that...he tried. How many times did he add oil? Regularly. But my little extinguisher put out the fire before any damage, and he was able to drive home. Cost of recharge: Free. The guy didn't even charge me when I went to have or recharged.
The fact is, when camping most of the time fire is involved. Either propane, white gas, or wood. It probably will never happen. But if it does, you need to act fast. As opposed to running in circles while yours, or some one else's pride and joy becomes an ash pile.
They don't have to be big. First alert makes one that lowes sells for just a few bucks. It's a little larger than a can of spray paint. Nor expensive. This one is $14
http://www.firstalert.com/fire-extingui ... ray/tundraNo,
smoke and CO detectors are probably overkill....unless you have a gas heater in your 55sq foot of heaven...then maybe. But a fire extinguisher is a must have. "It will never happen to me" DID happen to me. It might happen to you. If it does, I will say "told ya so..."