Before anyone berates me for going SLI, I was originally going to save for a single 1080ti, but by the time I could afford one, the GPU mining price cannonball was still in it's mid-air trajectory, and wouldn't go back to normal until the announcement of the RTX cards. At the window when GPU prices were normalized again, my patience has already worn thin, and if I were going to gamble at all in the used card market, $200 is all I was willing to spend.
So, with the reasoning out of the way, which current gen games scale well enough with SLI where 60FPS 4K is achievable on High settings, at the lowest. Medium may be okay depending on the game, but only if the visual trade-off isn't too great.
So far I have verified that Far Cry 5, Forza Horizon 4, and Batman Arkham Knight all run ideally for my tastes. Does anyone know which other games are good SLI performers?