[RichH]

My experience is that a Martec epicyclic shaped folding prop will have significantly less prop-walk than a fixed ''flat-ended'' prop. Ditto on the MaxProp when in an aperture (and I would like *more* prop-walk !). Both props (at equal dia. and pitch vs. the fixed blade) also are seemingly more efficient, so that you could also consider to reduce the diameter (and alter pitch) to lessen prop walk and still have an efficient set-up.
I found that the folks at Martec and (PYI) MaxProp are pretty correct in their predictions of performance characteristics, etc. on their props. ,,, but you have to discuss with them "exactly" what you want in performance.
:-)