Lenovo ThinkPad P70, external monitors w/Intel driver

I have a Lenovo ThinkPad P70 (muxless, internal is wired to iGPU, external monitors all wired to Quadro M4000M). I’m currently using it with the nvidia driver only, which is working fine, but I’d like to use the Intel/modesetting driver most of the time, with the dGPU used only for specific purposes (specifically, nvenc, vdpau, and OpenCL – compute, in other words, not rendering). This works fine with the laptop display, but any external monitors remain blank with no signal and nothing I’ve tried (thus far) works, including tweaks to the xorg configuration and XRandR commands.

I’m running OpenSUSE Leap 15.1 with kernel 4.12.14-lp151.28.10-default, xorg 1.20.5-lp151.580.2, nvidia 430.34 (OpenSUSE packages), Intel driver xf86-video-intel-2.99.917+git8674.25c9a2fcc-lp151.204.3.x86_64. I’m using KDE as my desktop environment.

Thoughts, anyone?

It’s for a slightly different laptop and distro, but this page might help: