I do not understand why anyone would risk their professional reputation by shooting with a camera that needs to be pampered during the shoot. Seems to be highly irresponsible to have to manage shooting time because of heat. Similar to managing a shoot because you do not have enough media or enough batteries to cover the full event.
The Canon C200B is available on B&H website for $3,999 brand new. I know it is not full frame and does not shoot 4k120p, but seems like a much better choice for paid work, if you need 4k raw from Canon, over managing multiple R5 bodies or R5 and R6 mixtures.