I create mine on a separate tool tab or what ever it is called. That way you can have it as the full height of the screen. Works quite well and beats the tiny size you have.
It wouldn’t take up anymore space on the PC than it does on the Mac. If you want to have the inspector windows floating over your workspace, you can move the tray. You can make as many trays as you want so if you want one just for the Scrapbook, make it. You could also move the tray(s) to a second display and make them larger.
If you are making your own scrapbook entities, lay them out on a page in LO and make sure they fill the paper space. If needed, reduce the size of the paper to fit tightly around the scrapbook entities. Here’s a quick example.
Created a scrapbook tray that spans the full height of the screen and sized my scrapbook paper size to fit the tray size at a good resolution for the items on it.
It works quite well for me as I find I dont need the scrapbook on the screen all the time. I usually only need it in the beginning stages of each sheet, then I use a combination of copy paste and eyedropper to fill out the drawing.
I must say the more I use layout the more I enjoy the way it does things. Coming from an autodesk back ground thats something.
With a few improvements I would be full time Sketchup Pro for my architectural work. Hopefully this month we will see some of those improvements.