My favorite version of Triumph is Kostya Kimlat's Culligula Triumph but that does require a cull. It does however avoid placing the last card on top.
I also do the Renegade version, and if you're getting called out on placing the last card on top might I suggest changing not the method but the patter or attitude? I have never got called on it and I think it comes down to the non chalant attitude. Don't even mention that the last card is going on top of the deck. The flipping of the cards face up and face down is confusing enough that the spectator should honestly believe you are mixing them randomly in random orientations so the "discrepency" of placing the last card on top of the deck should fly by. Don't make a move out of it. And once it's done just go into the cutting display to show some cards face up, some face down, some back to back etc. Hope that helps
And if you still want a method to avoid that, one way is perhaps place the last four cards face down on top of the deck instead of just the last one. So now you have, from the top down, three face down indifferent cards, face down their card, half of the deck face up, rest of the dec face down. Then shuffle off the top three cards until you get to their card and leave that on the top. I hope that made sense