quilting question.....

i have a tall skinny "baby" quilt made up of small 1/4 square triangles
(pattern/pale yellow, pattern, pale yellow) in an eye spy kind of set up
(there are 2 triangles of each kid print fabric in the quilt).
It has been hanging on my design wall for months trying out borders and
such. Nothin doin. The baby will be one on Jan 1st. Her room is done in a
beach/underwater theme.

I was planning on quilting a little flower in the yellow triangles and a
rounded off triangle in the patterned areas. But on the plane yesterday i
started doodling on a napkin. went from doodlin flowers to seaweed and
rocks and fish and boats and ........ thought maybe...........

maybe, just maybe, I could treat the backing (a very light purple on purple
which looks like sunlight dappled on water) as a whole cloth canvas and
quilt an underwater scene on it instead of focusing on the triangles in the
front.

Could i pull it off? would the pattern not matter on the front? or would
that mess up the front? should i save that pattern for another quilt?

I need to get working on this and am at a loss. This is the only thing that
sparked my interest so far, but i don't want to invest a lot of time into
something i'm gonna frog stitch. And i really wanted to get this to her
around her birthday.

ideas?

Kellie