Well, I have used plastic cans a french guy gave me after I punctured my aux tank. These were regular cans (10 and 25 lt) in which you usually carry chemical products. I must admit I used them only for 3-4 weeks or so, without ting them down so I couldn't see them wear. They were held by the luggage in the trunk & everything was fine.
If you plan to carry the canss inside the car & for a quick trip (which I understand yours will be), I'd give it a try
good luck & happy travel! Séb
Normal cars go to paradise, 2CV's go everywhere!