Im trying to narrow down choices on whether to go with dual psu's or buy one large one for my setup.

Im also struggling to find a metal rig on amazon that will house both the full atx and two psus (if i do dual psus).
Im going to use my 6700k/asus z170a main "server" machine/board as the mining machine (it runs plex/media/main files here), its on 24/7 so i figured it made sense.

Initially ill just have a 3080 and 1080ti, but i plan on adding a 2nd 3080 in a few weeks.

I've run the numbers on online calculators going with the full load scenario and adding 150, this seems to top out at 1175 watts (so the recommended is an 80% 1300 watt, typically $299 cost but now $476 single psu).

I already have one msi 80 gold 850 watt psu, if its safe enough i guess i could just add the second psu and use one of the dual adapters to connect the second?
https://www.amazon.com/gp/product/B08F9WGLP2/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
I assume with that i dont need the motherboard "split" cable i see referenced which often in the reviews is mentioned it caught on fire.

This is the rig i initially found on amazon, sounds as if it may fit two psus, but only if one is sideways and dangles:
https://www.amazon.com/gp/product/B08XJGG2YX/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1

Anyone have any comments on this setup and if it makes sense to go with a dual psu's here (and safe?), i guess safe if i make sure individual components are powered from the same psu (not split up)?
Thanks in advance