Yours is a practical need, where A7SIII seems to check most of the desired boxes. R5 and its 8K are far more esoteric at this point, kind of like the Imperial Bösendorfer ... but slightly more affordable.The only thing is - if you truly NEED an 8K camera, maybe you could afford RED? Or certainly UMP12K soon.
I just NEED 4K60p ATM. Does anyone NEED 8K right now? Perhaps a few do....
As to hacks, people mod anything these days, from the Mopar Chevelles to the Bedazzlers, from Tung-Sol-to-Svetlanas sub to the Daisy Dukes.