I know it is done with 4k textures all the time. How many 8k files are you talking about? Most of us, even with high end PC's don't run huge quantities of 8k files. I personally only use them for big meshes like mountains, quarries, roads and such. Also for female body and face meshes. Other than that, it is almost lost on the game, even with really tweaked enb's.
If it is a small bunch of 8k textures you could just try it, load it and check in game. I don't believe there is anything inherently bugged about Archive2's ability to pack them. Maybe one of the others will chime in and say different. It's a great question that I'm curious about now.