GT 740 as a secondary GPU in High Sierra

Hi all,

I'm just looking to experiment a bit with installing a GT 740 alongside my RX 480 in my current stable High Sierra build. I've read that for Sierra, I should be adding NvidiaGraphicsFixup.kext into Clover alongside installing the web drivers and adding <key>NvidiaWeb</key> to my config.plist, but I still get a black screen after booting. Removing the GT 740 allows everything to go back to normal. Is something like this possible?

My reason for doing this is to see if I can circumvent the need to purchase a BlackMagic DeckLink for full-screen colour monitoring in DaVinci Resolve. Has anyone tried something like this?