Long single shot consistent videos with complex detail are the holy grail, and there isn't any single simple method on our low VRAM (32GB or less) consumer GPUs. Nor will there be. As the author suggests, you can simply attempt to render a much longer sequence than 81 frames, at a rez that will fit into your VRAM (likely to be much lower than you want), and hope you get lucky (the models are only trained on 81 frames).

For an animated figure, you can, of course, use an external controlnet video for the motion, like a character doing a long dance. But you will have the issue of consistency of figure and background. Proper VACE, and blending of clips, will be needed here.

If one does simply generate a very long (say 10sec) low rez video, then v2v upscaling becomes useful as a second process. Wan2.2 is fantastic at this job. BUT you'll obviously need to do this in batches- and then consistency is a massive issue. The trick would be to only upscale every second frame, say, and then use VACE to batch upscale the untouched frames from the data in the previously upscaled frames. Of course, WAN2.2 doesn't have a good VACE solution yet.

Honestly, for most people- using the last frame of a video for the first frame of the next video is the only easy method, and is very simple to do. Use a colormatch node to prevent colour drift. And you can bring the clips into a VACE 2.1 workflow to blend the last 16 frames with the first 16 frames of two consecutive clips to try to give them better motion flow.

Last to first frame is the easiest technique. Then you just concatenate the resulting videos. I like to try different seeds until I find a 5-6 second clip that ends on a good frame. Then upscale + interpolate framerate 2x. And repeat until you have a long video. I have a couple examples of this on my profile. A "good end frame" is one where all the important bits for consistency are still visible. For example, I had a clip where a woman falls backward onto a bed, but the end frame didn't show her face, so in the next clip when she sat up again she was a totally different person haha.