Rowen your a smart man thats for sure. I am currently working on a simular project.
Designing my own top sheets has taken me a few diffrent directions. First if your ski is already made, think stickers, automotive spray paint and sharpe. With some planning you can get some pretty sick results. Especally with neon colors.
Going with a small manufacture that will replace the top sheet with yours. http://www.codaboards.com/. 40 bucks but creating an image large enough it a bit time consuming.
My way, keep some of the topsheet exposed, Cant go wrong with bare wood! thats what she said ha