In Colorado, the $6000 state tax credit applies to CPO vehicles that have not previously been registered in Colorado. Because of this, I would suggest considering CPOs outside of Colorado and confirming they weren't originally from Colorado. The $7500 federal tax credit would not apply since it can only be claimed on new cars. There's another thread somewhere that mentions Colorado considers cars to be used if they have more than 1500 miles on them...so the federal credit wouldn't be available.
Federal law is different than state law, and it's unclear that the federal credit isn't available. The IRS says that the "original use" of the vehicle must "commence with the taxpayer".
It's unlikely that Tesla would claim the IRS tax credit on an inventory car, and so it's likely that you could claim the credit without raising flags. While Regulation 12-6-102 of Colorado's Motor Vehicle laws & regulations requires dealers to title any demonstrator over 1,500 miles in their name and then transfer it as a used car, it would create an equal treatment problem across all the other states that don't require this practice should you get audited on that credit.