Marking rails for planing/shaping

There's tons of info and opinion re: how to shape the rails. It ranges from 'go by feel' to analytical breakdown of planing angles and progressions.  Not trusting 'feel', I marked out a number of things before picking up the planer.
This drawing shows the starting point - figuring out where on the rail is the apex, i.e., the farthest edge of the rail.  I wanted a 60/40 rail starting about 16" up from the tail so I put a dot 60% of the way down the height of the rail. Then I put dots 1/4" above and below my 60% dot and connected the 60% dots as well as those 1/4" above and below. Again, the digital caliper was very handy. I now had lines the full length of the rails showing where the outside of the rail should be and 1/4" above and below it.
For the harder rail below 12" I put dots 1/4" above the bottom. Between 12" and 16" I drew a straight line connecting the hard rail edge @ 12" and the 60% dot at 16".
If you look at Surfboard Design and Construction, the next step would mark out points for each planing angle. I did that for the first planing angle, a 1/16" release on the bottom of the board starting 3" in from the edge. Again, dots 1/16" from the bottom of the rail and connected w/a line using a straight edge. Did the same with dots 2" in from the edge on the bottom deck. For the other plane angles, I figured that as long as I did the same progression of planing surfaces as shown on SC&D, I didn't need to calculate exact edges of each of planing angle. Holding the correct angle on my 6" block planer would automatically set the right plane surface. I just needed to pay attention to how deep I'd go by watching the distance between the edge of my cut and the lines I'd put in to mark the apex. It seemed to work fine. The top of the board needed fewer planing angles than shown in SC&D because I'm not working with a foam blank - the ribs already defined the slope of the deck into the rails. 
The progression of my planing cuts for the 60/40 rails were:
1) 1/16" release around the bottom edge, starting 2" in from the rail
2) a 45 degree plane from the bottom edge to the line 1/4" below my 60% line.
3) a 30 degree plane from the top edge to .2-.4" above the top 1/4" line depending on where I was on the board.
4) a 45 degree plane with the bottom edge of the cut on the upper 1/4" line

For the transition to the harder rails starting @ 12" from the tail, I simply planed following the line connecting the hard rail apex and 60/40 rail apex.

At the end, the planing left a 1/2" flat spot at the apex around the board. I'd hand sand that to make everything smooth.