I've heard of folks in  northern climates waiting for frigid weather and pouring boiling water on the propellor while force was being applied by the gear puller. Now that winter's nearly over, maybe try cooling the shaft  with CO2 dry ice and hit the prop with boiling water.  Also, I believe "true" prop puller tools exist that contact the entire prop hub rather than the three fingers of a gear puller. 

Well I found that I had to remove the entire shaft to remove the old cutlass bearing which I ended up folding inwards to extract once the shaft was out.  As the shaft is aligned with the rudder, I had to drop the rudder, necessitating digging a hole in the gravel of our parking lot (not fun in an asphalt lot...).  If you are removing the entire shaft, you could leave the prop on it.  Neither the removal of the shaft (a couple of set screws) or the rudder is too difficult.  The latter requires a bolt to be removed from the cockpit and then fiddled with to get it back in (easier with two people), plus a lot of fun squeezing into the space aft of the rear cabin to remove the brass preventer collar and the aluminum steering control disc (then the latter requires some adjusting after testing for how the rudder behaves underway).  I used a couple of ratcheting truck straps up onto the gunwales to go back and forth to raise the rudder back up on my own. 

But back to the prop removal, it is simply being held by the taper of the shaft and the 'stickiness' of the brass on brass or SS contact.   The tightening of the nut has it very firmly 'seated'.  Put a torch flame onto the prop until it is hot all the way around on the outside edge, then use a long piece of solid metal with a mid-sized sledge hammer to tap it off with a few firm whacks on either side,  Leave the nut on their loosely while you bang on the inside edges to keep the prop from flying off and getting damaged it when it falls off.

You need to use a yellow "MAP" gas torch.  You need to get the hub pretty hot.  I used CRC Freeze Off Super Penetrant on the shaft as well.  I put the gear puller on, then heated the hub, then fully tensioned the gear puller.  Don't take the nut fully off as you don't want the prop shooting off when it releases.  Wear gloves and be cafeful.