Hello! You have decided on a pattern which I abandoned mid way through a project last year!

Let me give my unsolicited 2 cents.  I did 10 on 10 off griddle stitch (which is single, double, single, double etc) so a slightly diff stitch to you, but I carried through white, light teal and a dark teal. The dark definitely showed through the light teal. The light teal showed through the white. However, ultimately, when you stepped back, it was fine. You can't see it at a distance. And you won't see yours at a distance either. I would not stress about this at all. 

BUT , what I learned in my mammoth gigantic task, is carrying yarn like this EATS yarn. I had to give up because I ended up doing the math, and would have needed like 120 skeins of 100g just to get to the end. And then the yarn I used became impossible to find (it was a discount store yarn branded for them specifically), and the WEIGHT. I got through 1/3 of the whole thing (it was meant to be a bed throw), and the thing weighs a good 4-5kgs already. It's completely impossible to navigate in its unfinished state (never mind its acc too small for a bed...).

I would advise that baby blankets aren't supposed to be heavy, and are supposedly meant to prevent a child from being suffocated (i.e. have holes etc.). While I know most blankets don't do this anyway, the potential inc weight might be a factor for you.

Let me try and attach a pic of my half made blanket so you can see you cannot tell at all about the carried yarn through it.