I suggest sticking with the Star Alliance, if possible, which should (in theory) make interlining easier. That means using Avianca Brazil for your domestic flight. You can walk between Terminal 3 (AC) and Terminal 2 (most domestic flights, except for Azul and Passaredo). You will have to collect your luggage after clearing immigration, go landside, and drop it off again. Several airlines, including Avianca, have landside transfer desks in Terminal 3 for you to drop off luggage and get boarding passes. Turn left as you exit customs and enter the main greeting area. The desks are at the far end of the terminal, right by the entrance to the overhead walkway to Terminal 2.

It took me less than an hour to get from my international arrival gate in Terminal 3 to my domestic departure gate in Terminal 2 a couple of months ago. The line-up at immigration was short, and I did not have any checked luggage. On separate tickets, you obviously want to allow a lot more time. I wouldn't be comfortable with less than 3 hours.