A three bladed prop will make no difference. A folding prop (ie. a Martec Eplitec folding prop, etc.) will give you a little less prop-walk. A reduced diameter prop will also lessen prop-walk. The critical factor causing prop-walk is how close the tip of the prop comes to the hull / aperture.
Better to learn how to "back and fill": In backing down (with a right hand prop), use ''bursts'' of rpm in reverse to make the stern go to port; and, ''bursts'' of rpm in forward to make the stern walk to starboard, typically the rudder is not needed at all. Once you practice and are sure of the ''backing and filling'' you''ll usually prefer to have LOTS of prop-walk. The momentum (caused by idling in reverse) carries the boat backwards, the ''bursts'' of rpm will steer the boat. Dont be afraid to give LOTS of rpm (but dont soot-up the engine) to enhance the prop-walk effect. Most ''begining students of prop-walking'' dont give enough rpm during the ''bursts'' of rpm.
Practice in open water to and from a buoy, etc. Most boats back down best with the rudder held at 45 degrees to starboard... you''ll have to experiment to find what your boat likes.
Also practice turning the boat in a complete 360 turn (and within a boat length ... clockwise as well as counterclockwise) solely by using prop walk - leaving the rudder entirely alone! Start from a complete stop and turn the boat around completely without using the rudder by using just forward / reverse and the rpm lever ! Just remember that reverse make the stern go to port and forward makes the stern go to starboard.