Whenever I am building larger structures, I find it helpful to design smaller modular pieces that can fit together to make a larger structure. Maybe you can start with the corners to find a good way to outline the building, and then come up with some variations of tiling wall segments that you can repeat 3 or 4 times across the width of the building. Here are some examples of larger builds from my vanilla world that are just a few modular pieces put together into a larger structure:
I don’t know if this is the easiest way, but it has worked well for me. I have a folder on my computer set up to be accessible from the local network. When I need to put some files on the deck, I switch it into desktop mode where I have a shortcut to the network folder. Then I just take the files out and put them wherever I need them on the deck.