I can hear you - I went through this stage and a few tips from the sperts helped.
Maybe try sail forward a little more & as much weight as possible through the harness so you don't load the back foot - straight front leg & minimise weight through the front foot but use it to drive the board (straightish knee) - bear off a little so you can almost sail with front foot and harness - then gently slip the back foot in - you will probably go over the front a few times - we've all done it - but hey that's a step closer to learning to loop
check Guy Cribbs harness line guide - Harness lines in the right spot are really important - front line too far forward is an early planing killer and to far back is a catapult waiting to happen
Good luck
www.guycribb.com/userfiles/documents/The%20Truth%20About%20Harness%20Lines.pdf