My advice on the blue egg layer would be to go for pure Cream Legbars. The advantage with these is you simply don't need to raise the boys at all. You can sex them at hatch and non of the boys need be kept at all. This means less brooder space required, less pen space for growers and less than half the feed as you always hatch more males than females and the males eat far more feed.
There is a steady demand for blue egg laying pullets of any description and good quality pure Cream Legbar hatching eggs are in high demand. I forget what I charged for mine now - I think it was £2 an egg plus post and packing charges, but I know a lot of folk were charging far more
My advice would be keep your Marans IG crosses which you have obviously put a lot of work into and are pleased with. Remember not to try crossing on, stick with the original H1 cross so that will involve you keeping a flock of pure Marans and a flock of pure IG. The eggs from both of these pure flocks should find a good market as long as they are high quality birds, and you can set what you need to raise your preferred cross.
If you then kept another flock of pure Cream Legbars, you could once again sell the pure eggs, and by running some of the females in with your Copper Blacks can create a green egg layer and rear stock from that for sale
Doing it this way you only need to keep four pens and from those you can produce your pure eggs for sale and you hybrid eggs to hatch.
Just another line of thought for you