Airspeed error.
I'm not sure flying to the numbers (ie. 65Kt.) is what you ought to be doing here.
You will notice that if you quickly release the rudder whilst in a side-slip there will be a marked change in IAS, which suggests to me that there is significant airspeed error whilst slipping an RV- and the amount probably dependant on your particular pitot/static setup. (How many builders have noticed that the static vent position is different on the fuse plans to that marked on the documentation accompanying the pitot/static kit.) You ought to be flying the aeroplane by feel as much as the ASI.
RVs do not delight in side-slipping with the panache of Tiger, Cub or Auster. You can do a left/right/left side-slip in the Tiger, after the flare, to wipe of the airspeed whilst flying level holding off for the landing. In my experience RVs do not lend themselves to this kind of manoeuvre, for what ever reason, and so I confine slide-slipping to above 500'. If I am still too high by then I'll go around.
Never forget that crossing the controls up at low speed is an excellent way to enter a spin.
I also suspect that Vans deliberately made the rudder forces high, to protect the Fin. Remember that unlike the wing and tailplane, the fin is asymmetric (it only sticks out one side) and so the rudder applies twisting forces to the Fin.
Now, this is only my personal style, but I confine side-slipping to above 500', mostly on base. I do NOT push on full rudder just because I can, I only apply what I feel is a reasonable load.
But I do enjoy a huge side-slip in the Auster, right through the flare and kicking it straight on touch down.
IMAO
Pete.