Congrats on the R5C! Its such a beast of a camera but yeah, trying to focus 8K on that tiny flip-out screen is basically a nightmare. I went through the same struggle when I first got mine. Honestly, if you want the best experience, you should definitely grab the Atomos Ninja V+ 5.2 inch 8K HDMI Monitor Recorder. I have been using it for a while now and it is the perfect match for the R5C. It handles the 8K 30p (and even 60p with the right power) RAW output perfectly. The color science matches up really well once you load in the Canon Log 3 LUTs. For brightness, it hits 1000 nits which is great for outdoors, tho I still recommend a small sunhood for those super bright midday shoots. About that micro-HDMI concern... you are right to be worried. It is super flimsy. You absolutely need to get a cage like the SmallRig Camera Cage for Canon EOS R5 C 3890 because it usually comes with or supports a dedicated HDMI cable clamp. That little piece of metal is a lifesaver and stops the cable from wiggling and killing your port. For power, since the R5C is a total battery hog, I stopped using internal batteries entirely. I use a V-mount battery to power both the camera (via USB-C PD) and the monitor (via D-Tap). It makes the rig heavier but you can shoot all day without stressing about the camera shutting down mid-take. The Ninja V+ is definitely the way to go over the Blackmagic for Canon RAW workflows imo.

tbh for daylight visibility, the Blackmagic Design Video Assist 5 12G HDR is a beast. 2500 nits means you wont need a hood. It records BRAW tho, not ProRes RAW, so keep that in mind for DaVinci Resolve. Also, definitely pick up a SmallRig HDMI and USB-C Cable Clamp 3637 to keep that micro-HDMI connection from wiggling and killing your port.

Totally agree on the cable clamp. Micro-HDMI is basically a disaster waiting to happen. Just factor in the cost of extra batteries too, because bright screens definitely chew through power.

I'm very happy with the Atomos Shogun Ultra 7-inch 8K HDMI Monitor Recorder for my R5C setup. The 7-inch screen is a bit bigger than the Ninja but the 2000 nits brightness makes it way easier to see in direct sun without needing a bulky sunhood. It handles 12-bit ProRes RAW recording like a champ and the build quality feels very professional. To fix the battery situation, I've been using the SmallRig VB99 Pro V Mount Battery. It's small enough to stay portable but has enough juice to power both the camera and the monitor through a D-Tap to DC cable. It's much more reliable than swapping those tiny internal batteries every 20 minutes, ngl. For the HDMI connection, I'm satisfied with the Kondor Blue Coiled Micro HDMI to Full HDMI Cable. The coil adds some tension relief so you dont accidentally snap the micro-HDMI port on the camera body. No complaints so far, it just works well for high-bandwidth 8K signals.