Originally Posted by
Schwanker
Or open a new Traditional IRA with zero balance just for this purpose.
If I'm reading you correctly, I think you may have missed the point.
You have to consider ALL of your (traditional) IRAs when calculating the pro ration, whether in one or many accounts and/or multiple custodians, without regard to "which" IRA you use to actually perform the conversion
Opening a new IRA may or may not be desirable (for purposes of the DPSP, I suggest opening one with Fidelity, as it will make the process much easier), but it does nothing to help with the back-door Roth.