I might be headed to EZE from EWR

I've read the other threads on getting to EZE:
1. via PTY on Copa from MIA
2. via PTY taking CO EWR-PTY and overnighting in PTY
3. via ATL on the DL codeshare
4. abandoning CO and taking AA JFK-EZE

My fundamental question is: Under the assumption that I'm happy to burn some miles, what's my best chance at getting into the front cabin?

Also, I can't even figure out how to book the Copa flights from EWR online as a single ticket.

Umm. Also again, is it possible to burn miles for a Copa upgrade to EZE? From the website, it doesn't seem to be allowed except from Y.