I generally don't have range problems in the spit14. It's way better than the 5/9/16.
While it may use up the DT climbing to 20k, that means you still have full internal fuel up at 20k, and you're able to cruise at high speeds with very low fuel consumption. You can reduce RPM like mad!
I usually fly it for its range.
I wouldn't complain if the large-size DT were on, but I don't think it's a major failing point for this plane.