My bent trike is set up .........
53t/38t double chainrings on a Schlumpf HSD on the front.
A 21 tooth sprocket on my Rohloff built into a 20" wheel.
Try 9.5" to 172" in 24 steps.
I've found this setup works the best for me.
I did send the hub back to Rohloff after two years use to be checked over due to the silly low first gear, it came back with a report saying "no problems found with it".
One downside of my rig is weight wise the trike+trailer+camping gear probably comes in close to 60 kg.
But due to the silly low first gear, as long as I keep traction on the back wheel, I can pedal up anything ........