Ask Lemmygrad

Second, who is boarding a packed, disease-ridden sailing ship for a perilous months-long journey besides those with few other options?

The diggers and the levellers; both key figures in america, look em up. Religious fundamentalists who wanted freedom for white men and genocide for everyone else. They split from there lords over the contradiction of 'you shall not kill' in christians conciding with the class conciousness emerging in the serf class as they slowly began to read.

That was one of the first questions that they asked 'if it says here you cant kill but you killed to gain the land we serfs work then you are not holy' basically.

First, what does proletarian even mean when capitalism is still in the takeoff stage?

You're right that workers in the domestic system at that time, the pre-cursor to the proletariat, would not have the means to settle the colonies unless a corporate sponsor really needed their specialties.

Second, who is boarding a packed, disease-ridden sailing ship for a perilous months-long journey besides those with few other options?

All ships were disease ridden then, they are still disease ridden today, look at cruise ship statistics. The deadliest route to California from the US was a boat to Panama, taking the train across the isthmus, then a boat to San Francisco, an expensive itinerary - because it was the fastest. Highest rates of death occurred in this route due to disease. It was the poor and cheap who took overland wagons (which still cost a lot).

It appears that Sakai's answer is that land hunger was so severe that, yes, petty bourgeois individuals would be willing to endure it to have something like the standard of living they had been used to.

the sons and daughters of the middle class, with experience at agriculture and craft skills, were the ones who thought they had a practical chance in Amerika... What lured Europeans to leave their homes and cross the Atlantic was the chance to share in conquering Indian land.

Here is a quote he takes from ""Social Origins of Some Early Americans". In SMITH, ed., 17th Century America. N.Y., 1972."

Land hunger was rife among all classes. Wealthy clothiers, drapers, and merchants who had done well and wished to set themselves up in land were avidly watching the market, ready to pay almost any price for what was offered. Even prosperous yeomen often could not get the land they desired for their younger sons...It is commonplace to say that land was the greatest inducement the New World had to offer; but it is difficult to overestimate its psychological importance to people in whose minds land had always been identified with security, success and the good things of life.