Could you do a trench drain? That would look pretty cool with the planks.

I was going to suggest the same thing, I used a trench drain in my shower and it was a little confusing but once you get into it, it went quickly. The nice thing is you don't have to deal with the heavy mud shower floor. I purchased mine from quickdrainusa.com.

The short answer is that yes, with a standard center drain, it would probably be very difficult to achieve the proper slope with the wood plank look tiles. A trench drain would work. Another option is to use a teak shower tray over a tiled floor.

Here is a link that might be useful: Teak shower tray examples

Crossville tile Wood Impressions has a mosaic made with their wood look porcelain tile. Comes in 6 colors of wood. I would use the larger tiles somewhere else in the bath to tie it in.