You do great! I remember when I first came to the boards and you posted one of your helpful diagrams and then it took me another 6 months before I figured out how to post pictures. I'm used to drawing with pencil so use patterns but my designs don't translate well to other people.
Well, they will be 4-patch units once they are laid out, they just start as a rectangular subunit so you can cut the correct number of squares.
I guess what I would do is make all my L blocks first, you could sort your fabric into light/dark or just depend on contrast. For each L block I would make at the same time the two units of the contrast fabric.
Then you just layout the blocks, starting with the solid square and touching the L blocks on the center point until you like the row. Leave the space for the 4-patch row and layout the next L block row. Then you go back and match the contrast fabrics to their correct L block and make the 4 patches.
To make the setting triangles, you would still use those 2-patch subunits. Include a slightly larger rectangle of background for the other side, basically making a Reverse L block (contrast in the square, background as the L) and then trim across the points remembering your seam allowance. That's the purpose of the slightly larger piece, for a better seam line.
Same thing for the next set, layout the L blocks, then fill in with the 4 patches as you develop the layout.
Unless you want the color to move in a deliberate way across the quilt, you really only have to layout out each row so it is pleasing to you.
I have a small house and suffer from limited layout space myself. The only space I really have for a design wall is the back of my sewing room door and it just isn't enough
So when I need a large space I have to layout on my queen sized bed which can be challenging laying out a quilt large enough for it.