37s 3.8l , 42RLE auto , 5.13 gearing = I know what OP contends with. If aproching hill , Off I turn the OD.
I manually shift the ‘11 ( no tap shift like 12 & newer) from 1,2,D then on flat straights , “D”+OD . Some hills even require downshifting into “2” . Done this for 90,000 plus miles. Tuners can sortof accommodate gear and shift points but not well enough to use it as an auto completely , fwiw.
Superchips offers a tranny tuner add-on. It made a world of difference getting the tranny to downshift on hills. I had it tuned so any uphill load with slight throttle input would kick her down, but on level ground it took a bit more throttle to get it to downshift. It was still a bit of a compromise between these two situations but it was drastically better than stock.