Well are they the type of parents that would be sceptical for you to go anywhere no matter who was supervising you because of the feeling that they cannot be there to watch you themselves? Because in that case it'd be extremely difficult to persuade them. But if your uncle is going with you I don't see the problem. Just be good , and show that you are responsible to take care of yourself should the circumstances require for you to look after yourself , obviously your uncle will be your temporary guardian but he is not your parent and therefore cannot mother you for the whole journey so you will have to demonstrate to your parents that you are mature enough. Now that unfortunately is down to you only.
Speak to them kindly, don't get impatient or rude. Ask them , tell them you will be as good as ever! Beg (that's what I do) , lol occasionally I'll drop the emotional blackmail scheme, but that may be over the top and then they may think how immature you are , depending what your parents are like! The only normal way is to just be an adult about it , and ask kindly , and ask them to trust you and give you a chance. 8) Good Luck!
