jRyles,
As you get older and experience more of life's lessons, you'll find that many things you think may be problems don't end up being problems. Have patience, and don't fight battles until you need to. Worry about this issue in 2.5 years. Also, research some group rides that are sponsored/supervised. When the time comes, having a clear plan with an organized ride with many riders may be more palatable to your folks.
Patience is s sign of maturity. If you don't have patience to let this matter lay dormant for a while - you probably are too immature to do a bike tour! If you can master yourself, and chillax about this for a couple of years, then your parents may note this maturity.
Until then, find a good bike for the type of riding you like and practice and get exercise near your home.