Not sure how well this works with clipless systems, but back in the old days of slotted cleats and toe straps, the trick was to put the cleats on but with the bolt(s) just "finger tight" so they could "roam" a little while you rode...

Then go for a ride in your natural position, and after a ride, viola! Tighten up and that's your natural fit.

Or from the super-old days....nail them in.