You know what's coming next: The Rats get their witnesses, Trump does not.
Should put witnesses from each side on each vote, if not doing them all in one vote... Since when does the defense not have the right to call who they want? The House could have called whomever they desired after they finally voted.
This will spin out of control, neither the Democrats or the Republicans are going to be able to shape it. My only thought is that the best approach would be to flood the zone. Insist on every every character in this soap opera who appeared on the stage, no matter how briefly, to appear as a witness. This will be unpalatable to the Democrats and will cause them to reverse their demands.
If they do that, they will make the GOP a permanent minority, just as many of them would like.
Trump gets witnesses that plead the Fifth. The Rats get witnesses that hate Trump and shade the truth.