Well, what I do is make a posterboard blade template and trace it on the pipe and jig saw it out in a few minutes. I made my blades similar to yours with the bottom (trailing edge) straight all the way down to the tip. It make it easy to make them the same.
Here's a picture of my last pvc blades:
Maybe make the blades about 2" wide at the hub where it screws down.
It is up to you how well you sand the edges down. If you don't make the "Magnetic Decogger" you might want to make the blades 3.25" at the widest point instead of 3".
Thats a good idea about balancing them on the shaft with a little oil.
It is easiest to have a postal weight scale to weigh each blade as you make them, to get them all exactly the same weight. 5 blades should be even easier to balance.
If they are off balance, I just tape a 3/16" little bolt/nut and washers to the blade up near the hub to which ever blade is off, and when It balances, I then drill thru the pvc blade and bolt the # of washers in that location.
I don't know where you live, but summer is not so good for smaller mills around here. The winter is quite good though. Where I am at in Ohio, my solar panels probably do on average TEN times more daily watt hours than my 6 foot mill in the summer time-- BUT my 6 foot mill probably does TEN times more average Watthours than my solar panels in the winter months! It completely reverses. In the spring and fall they seem to be about equal.
You might think about getting solar panels ASAP. (or a 10 foot hawt 40 ft in the air! ha)
-Good luck.