Lowes should sell glass for cheap and they even cut it there. A 10g sump takes 9 3/4" wide baffles. If you don't have a lowes, a picture frame studio should have glass, and cut custom glass pieces. The glass doesn't have to be very thick at all - especially in such a small sump that isn't very wide.
I don't see any reason why you couldn't have a fuge first. However, some people say that a skimmer will skim out copepods if placed after a refugium. I don't know if it's true or not.
Also, think about this... When your overflow pipe comes into the first chamber, it is just water flowing at one certain point, but when it goes over the first baffle (in the diagram) the water flow spreads out evenly over the macroalgae in the middle chamber. If you do run the pump at full capacity, you will want a lot more time for microbubbles from the skimmer and overflow to diffuse and pop before reaching the return pump chamber.
Then again - like I've been saying this whole time - it's your tank, do what you want!
Something that would also help eliminate microbubbles is to add a small piece of filter floss between the baffles before the return pump chamber and also add a PVC 90elbow to the return pumps intake pointing downwards towards the bottom glass.
I wish I could add one baffle to my old 10g sump and ship it to you. It would make your life a little easier. lol