I would bring the clean urine either way. What the hell, you already have it. Just hide it really well. Remember that some places may ask you to empty your pockets, so I would hide it in my underwear instead of my pants.

Start out using the clean urine. If something goes wrong, like maybe the temperature is not right, then you can fall back to giving a diluted sample. You win either way, but the clean urine is a 100% win.

Good Luck!