Thank you for your suggestions! Very helpful 
When I did some googling earlier I found that this person tried UpdateTextureRegions Updating a texture by code at every tick? - #2 by Pino_of_DFT_Games but since he had poor performance with quite a small texture I didn’t investigate any further. I will give it a try 
I will give option 1 a try as well When I was googling I came across examples of updating texture data in one batch at runtime e.g. https://www.orfeasel.com/generating-procedural-textures/ but I discounted it since it requires UpdateResources which the above forum post also mentions kills performance completely. That is why I thought that I was totally on the wrong path.