For me, the most reliable way to set off dawn phenomena is to NOT EAT anything.
And the most reliable way to thwart it, is to eat something.
It can be so ridiculous that sometimes I need more insulin if I don't eat anything, than if I do eat something carby for breakfast.
As a result anything found by doing a "basal test" involving fasting is just garbage. IMHO. The fasting is an excellent way to see the dawn phenomena if that's what you WANT to see!!