Not sure about when check in would be open. You could always try Gol international as they are DL partners. If you're flying on Gol from Florianopolis you could try to check your bags through with them.

If that fails, there is a Plaza Premium Lounge pre-security at level 2 (VIP Parking) which is accessible for R$85. Never been to the domestic lounge, but it looks like they have showers, etc.

https://www.plaza-network.com/
http://www.riogaleao.com/upgrade/

The latter is only available in Portuguese, but if you click on Plaza Premium Lounge a pop up will appear with the lounge options (international, or pre-security domestic)