Firstly, I dont know the legality of this.
Secondly, is 10L going to make enough of a differance?
Thrid, it's up to you whether you want petrol in the cabin. It would only be dangerous in severe turbulance or a crash landing where the integrity of the containers might be compimised. Think about it a bit. Have you ever seen petrol ignite? Its scary. I once doused some rubbish in a petrol/diesal mix in a 44gal oil drum with the top cut off. I threw in a lit rag from a few meters back, but it still shocked me. The entire contents of the drum went about 50ft up, and came down all over the place allight.
Having said that, I once drove 20,000 miles around Oz with 20L of petrol under my bed in the back of my van. Can't say I'd recommend it though.
If you're going to a strip with no fuel, it is possibly short, so why not have a fuel stop soon after departing the strip, that way you'll be light for the strip arrival and dep.
Bush planes often carry fuel, but they are often in 44gal drums which are incredibly strong.
Wouldn't bother personally.