you should be using the pump attachment that fits over the bladder inflation nozzle - not the pump attachment that fits inside the nozzle. If you do this it should be worlds easier.
How does that work? i don't think I'm understanding that right. Picture?
I had a membrane valve that was too tight on an 2007 bularoo so used a screwdriver to carefully bend it out of the way. Made it much easier to pump. No longer worked as a stopper valve, but like you said, who cares on a one pump kite. Don't know if this will work on the North valves though, they seem different. Will have to take a closer look. Be careful not to cut the bladder.
You can also just leave the deflate stick in the valve when you roll up the kite. That should stretch out the valve a bit. This is a lot safer than the screwdriver.