Update: I'm in the process of doing a test render with my comfy workflow, which I'll post shortly. It may be able to handle 81 frames at 720P on a 4090. Use this ComfyUI module to load the checkpoint: https://github.com/silveroxides/ComfyUI_bnb_nf4_fp4_Loaders

These are NF4 Quantizations of the Wan video generation AI. They work really well.