Sarcasm button on, an IPA that finishes at 1.020 is a balanced one!
With the amount of hopping, having a beer that finished at 1.010 will be out of wack. As I eluded, I also do not use alot of crystal, and the Southern Cali versions I had last year did not either, a light dusting is all that is needed. For full grain brewing, munich is used alot as well.
So 50% of your BU's into your boil, 50% from the whirlpool step is the approach. You will get the bitterness if using any hops over 10% aa.
As an example, a light ale I make at 1.041 using topaz and galaxy, I bitter to 8 BU with the whirlpool of 10 minutes and a 45 min run-off gives an additional 17 BU's. I've ran these thru a spectro, so the numbers are right.
I am assuming the wort will be boiled?