Alan, attached are a few pictures I just took.  They are as-is, and will look better once I sand and varnish.

The first one is of the proposed slotted rail.  The thickness of the apacer and long rail is the same as on my canoe and that looks nice.  I would like to use this light coloured wood for the spacers to accent the decking on the seats.  Make the rails look more delicate too.

What do you think?