If I recall correctly from my one visit to PEM (which was several years ago), you'll deplane on the tarmac via stairs and be directed into the arrivals area, which is separate from the departures area. I very much doubt you'd be able to talk your way into the departures area of the terminal, meaning in all likelihood you'd have to reclear security. Check-in at PEM was maddeningly slow when I was there, so if you aren't able to obtain your boarding pass in advance for some reason, you'd be in a very difficult spot.

As far as weather goes, on that route I'd be most concerned about the CUZ-PEM leg being delayed enough to impact the turn at PEM -- it's very likely that you'd have less than 1h20m to work with. When I was there, for example, the weather conditions at PEM deteriorated as we were on final approach, no more than 1000ft off the ground. We climbed sharply and headed right back to CUZ, where we sat in the terminal for two hours before reboarding and trying again. When we finally arrived at PEM, the return flight to CUZ began boarding very shortly after everyone had deplaned.

If you end up in PEM after all, for what it's worth, Refugio Amazonas or Posada Amazonas would be well worth a visit (I stayed at the former and my wife's cousins have stayed at the latter).