Yes, possible but expensive
yes, thats possible. I did that trip and had the same questions. Now, for the North Americas (US and Canada) that shouldn't be a big issue, just be sure that you have a high enough 3rd party liability, otherwise you will be bankrupt, if in an accident (which hopefully will never happen) there is a person damaged...
From Mexico onwards until Argentina I used "American Underwriters". They cover either 3rd party or total loss etc. Means Theft.
I met lots of people that did not have any. And there are countries that make you buy their accepted insurance at the border (such as Mexico) no matter if I had my AU cover.
So decide for yourself, you can chose by country, by time etc.