Possibly, but this would have to be on the Geom then, not on the PandaNode, since the original PandaNode isn’t stored in the cull process. And it can’t be in CullBin*–addObject, because that is called during the cull traversal, so it has to be called during sort or draw.
This isn’t necessary though, because instead of a frame index, you could simply use a “pass index”; a number you increment for each cull pass you do.