I don't have a problem with suck back. Once the beer is finished, I do a D rest in the fermenter (if needed, normally it doesn't) and then do a closed transfer to a CO2 purged keg. I then cold crash while having CO2 pressure on the keg. If I have to add gelatin to clear the beer, I keep a slight positive pressure on the keg when I open the lid to add the gelatin. This helps minimize O2 pickup in the keg and prevents suck back when I open the keg. It is a simple solution and works well for me.