To get your head around exposing for VLog_L this document was a life saver for me:

http://pro-av.panasonic.net/en/dvx4k/pdf/ag-dvx200_tech_brief_vol6_en.pdf

That document mentions the DVX200 but as that also uses VLog-L I see no reason to not use it. Also the DVX200 has the similar limited dynamic range of the GH5 (not being a Varimac LT etc).

Summery from document:

VLOG-L gives the widest dynamic range and the most post-production exibility from a DVX200. If your project can afford the time to conduct the proper post-processing required, VLOG-L gives you the broadest canvas on which to paint your images. Exposing properly for VLOG-L is the key to getting the best results; aim to expose an 18% gray card at about 42 IRE, keep your Caucasian skin highlights to below 55 IRE, and set your Zebra 2 to 75 IRE to keep from clipping highlights.

Take home notes

• Caucasian skin set Zebras to 55 IRE
• Set top end Zebras to 75 IRE
• Set 18% grey card to 42 IRE (not usable in GH5 as we can't set Zebras that low in VLog-L)

Here is an image of my Keyboard with FC in VLog-L & Zebras as 55IRE:

One really cool thing about custom LUTs on the GH5 is that once you install them they are saved onto the camera. So you can have a spare small SD card with as many LUTs as you want- then install them as you see fit. The camera will remember the last installed LUT's. Currently there is space for 4 custom LUT's on the GH5.

EDIT: Just noticed my shutter is 240 degrees, I assure everyone that I normally use a 180, this was simply a pick up and play moment. Also normally my battery is fully charged. :-)