The PD tank looks great, but is expensive to get and any rider above a certain height is precluded - as your knee is further forward than the side step.
I just got a kevlar version of the PD tank from TAG in Italy, they still have the mould from back in the 80s and can make reruns. See below for Desert Piston's example.
The side step is pushed forward (approx 40mm) and has a more of an open angle, so should work with the legs. Its light and has internal baffles to limit petrol slosh.
Can post some photos if y'all interested