I've stared at this for awhile, and I can't think of anything better.

My original thought was that we would put this code at the end of __wt_rec_write (the reconciliation function), that is, if reconciliation was about to return EBUSY, check and potentially split it.   That said, that ignores the new requirement that we're going to update like we evicted a page, but not discard the original page.

So, as I said, I don't see any better choices.