I would suggest the SmallHD Action 5 5-Inch On-Camera Monitor. I used a cheap ultra-bright panel for a car rally once and the colors shifted so bad I couldn't judge exposure. It was a total nightmare. Be careful with the battery drain tho... these things eat NP-Fs fast. Make sure to grab a solid sunhood or you'll be squinting regardless of the nits.

Building on the earlier suggestion, id look at the Portkeys LH5P II 5.5 Inch 2200nit Wide Color Gamut Monitor. Its incredibly bright for outdoor shoots and the wireless camera control is honestly a game changer.

Jumping in real quick since I just went through this. I had a car shoot a few months back and realized a few things about the setup I was using...

• My first time out, I actually had more issues with the cable than the screen itself. The thin high-speed cable I bought for gimbal clearance kept dropping the signal when I hit high frame rates, so definitely dont cheap out on the connection.
• I ended up going the DIY route for power. Instead of stacking heavy batteries on the back of the screen, I rigged a cable to run everything off my gimbal battery. Saved my wrists on a long day of tracking shots.
• Heat is real tho. My unit shut down once in the sun, so I started taping a piece of white gaff tape to the back of the casing to reflect some of that direct heat. It looked a bit janky but it worked to stop the thermal shutdowns. Honestly, for car stuff, the mounting hardware matters as much as the screen. If your mounting arm is floppy, you wont be able to see anything regardless of the nits.

Ive shot a lot of automotive stuff and you definitely gotta be careful with the heat and glare out there. For $600, I would suggest looking at the Atomos Ninja V 5 inch 4K HDMI Recording Monitor. Its a staple for a reason and handles the A7S III 10-bit feed without breaking a sweat, though be careful because it does eat through batteries fast. If you're gonna be in direct sun in Chicago, you might want to consider the PortKeys LH5P II 5.5 inch 2200nit Camera Control Monitor instead. Its way brighter than the Ninja and lets you control camera settings via Bluetooth, which is huge on a gimbal. Just a heads up, make sure to get a high-quality cable like the Kondor Blue High Speed HDMI 2.0 Cable or you'll get those signal drops and lag you're worried about. Cheap cables are usually the culprit, not the screen. Honestly, dont risk a cheap cable on a pro shoot.

Bookmarked, thanks!

Same boat, watching this