Codecs and recording quality/resolution/fps/space

Apart from the monitor screen benefits I bought a Video Assist 5" for higher recording quality.

However after getting it fired up, and then finding about the Sandisk SD card problem I have now found only two 64GB Sandisk cards that work.

The problem is I need to record 50m of footage in one take and Using ProRes I will only get 29m, even LT only brings this to 41m and as I discount Prores PR (I assume PR=proxy) due to 1/4 resolution, then only DNxHD 45 gives me enough recording time on 64GB.

After doing some research on lower qaulity DNxHD, the information I found indicated DNxHD 45 is limited to 720p, yet my test recording is saying I do get 1080p 50fps.

I only want to record FullHD and will have to accept more compression and possible frame rate reduction.

Currently I'm using a Panasonic HC-V770 as the source and this always seems to show 1080 50. I don't seem to be able to reduce the fps (what am I doing wrong?).

Is the DNxHD 45 at 1080p 50fps 'real' or am I losing something else I'm not aware of?

Another option is to get a bigger card and stick with ProRes HQ. The Kingston Canvas React 128 GB works in the Video Assist (I've tested) and is very cheap (about $30).

Kingston Digital 128GB SDXC Class 10 SD UHS-I100MB/s R 80MB/s W Flash Memory High Speed SD Card SDR/128GB

This is the one you want. They make even larger-capacity ones, up to 512 gb, but I haven't seen reports from tests of those so you'd be taking your chances. Many people have reported success with the 128 gig cards (and failure with lower-capacity ones).

Get yourself the Aja Datacalc app Works great to mix and match data codecs vs memory vs recording times

Another option is to get a bigger card and stick with ProRes HQ. The Kingston Canvas React 128 GB works in the Video Assist (I've tested) and is very cheap (about $30).

I had read about that and the Samsung Evo Plus, so I've ordered one of each to try. I'll order more of whichever is better.

However, although space is a consideration, what I don't fully understand is how when I search for info on DNxHD 45 it suggests it is a 29fps 720p resolution, yet the Video Assist seems to have recorded a 50fps 1080p.

Will the DNxHD codec just take whatever bit rate you set it to and 'fit' the stream into that?