Was working a bike shop as a teen before my trip. I stripped that varsity bike down to the frame. Carefully put new parts on it, made adjustments, road it to and from home, school and work for about a year while repeatedly looking for potential wear and tear and complete failure.
What tools I needed, what parts and spares were best etc .. a bivy bag, sleeping bag and a homemade sleeping bag liner made from old bedsheets and one change of clothes w tools , spares and a water bottle and we were off. It was a fun trip all the way .....very few breakdowns and all were easy to fix.
In ‘72 my older brother rode cross country from San Fran to Rehobeth Beach Delaware on a Schwinn Super Sport. He was with the Christian athletic group Wondering Wheels.
Those Schwinn’s were built to last.
Your trip as a junior in high school took cajones!