Penny Edring

So I'm looking at getting an E-GPU enclosure and a AMD graphics card of some sort to run on my 2017 5k iMac. I'm really wanting to run Ultra graphics with playable frame rates, but I don't know if that's even possible! Is anyone else in the same boat? Can someone make any recommendations as to what E-GPU and AMD-based graphics card that would do Second Life justice? I already know MacOS and Second Life don't really like each other, which is a shame because I only want to use MacOS. Specs are: iMac (Retina 5K, 27-inch, 2017) Processor: 3.8 GHz Quad-Core Intel Core i5 Ram: 24 GB 2400 MHz DDR4 Internal graphics: Radeon Pro 580 8 GB