Minimal Reference Video Burn-ins for Ultra-Low Budget?

Hey everyone,

I'm Simone, a 2nd AD currently working on a passion project. It's truly ultra-low budget, think borrowing gear from friends, lots of favors, real indie stuff. We're shooting on a mix of a borrowed LUMIX S1H and my old FX6. Audio is mostly Sync E timecode synced to a MixPre-6 II, but we won't have dedicated DIT or extensive post-production resources.

We're trying to keep things as lean as possible, especially concerning post-production time and software costs. My main concern is avoiding sync disputes down the line without blowing our tiny budget on fancy burn-in systems or heavy processing. Right now, we're just recording with the camera's native timecode burn-in, but I'm worried that might not be enough.

What are the absolute minimum 'burn-ins' you'd recommend for reference video specs on a shoestring budget, specifically to ensure easy sync and avoid headaches, without adding significant software or processing overhead?