Don't worry about the crowds. Should you do that last 200k and love every minute, will you find the motivation to return? Fall into the "Been There, Done That" syndrome? Leaving Roncesvalles there is something almost intimidating as you stand near that Santiago de Compostela 790 kilometers sign post - a month later you are totally overwhelmed emotionally, spiritually, and physically as you walk triumphantly into Santiago. I am not putting you down, 200 kilometers is an accomplishment in it's own right but it cannot compare with that first time walk though Porta do Camiño headed for the cathedral and that 790 sign post in your back pocket! My opinion? Start at SJPP and walk as far as you can, see if this is what you really imagined, enjoy all which is offered, the scenery, the art, the architecture, the comaraderie then later, when you have the time, come back to SJPP and do it all!