Battery Life and Memory Capacity

I'm going to be in the field, and have never shot so much video remotely (or not that much either at once).

Likely it will be about 3-4 hours of video, lots of start and stop, focusing, interviews, b-roll video, etc.

How many batteries would you bring (I have 4 Batteries)?

Two camera bodies.

How much memory (I was thinking about 64 GB or more)?

I'll also bring a grey card, reflector, lenses, flash (For night photos if needed), digital audio recorder, with extra AA batteries.

What am I missing or mis allocated for this? I'm trying to plan well. Suggestions?

Good question, I'm wondering the same if I need to buy a battery grip.

I don't think a grip is needed, I can just swap out for a fresh battery. I'm thinking a battery will run about an hour and 15 min or so in Video mode.

I don't actually own a dSLR that has video capability, but to find out how many batteries and cards I need I would run some tests to see how much video I can get on my largest card, and how much battery is used doing so. Extrapolate from there how many cards/batteries you'll need and then add an extra of each to be safe.