After being prompted into action by the efforts of sk8ment in a recent build thread, I have made a start on something not conceptually dissimilar.
Sizing began at a length that would fit across the rear compartment of my car with the back seats folded down, and at around 5'4" I'm going a full foot shorter than I ever have before (I'm 6'2" and 90kg).
Once I decided on the nose/mid-point/tail thicknesses, and rocker dimensions, I realised that if I was prepared to have a completely flat deck line running from nose to tail I could make it from a 3" slab of XPS. It looks like it's going to end up approximately 20-21" wide, with nose and tail widths of about 17" and 19" respectively.
From the deck I intend to just chamfer down along the outline edge, where required, to get the rail thickness I need. I will add some deck concave to try and tone down all the width/thickness and get some control back. I have applied a gentle roll across the bottom to assist with this as well. Rounded pin tail shape for the graduated, analogue motor control available on the toe side, combined with a squash tail shape for the on/off, digital nature of the heel side.
I am working just with a saw, and an assortment of home made hand sanding apparatus, marking tools and improvised jigs to try and help me make things even, and ensure I create as little mess to clean up as is possible.