Can I trim the excess fat off this? Just get it to a rectangle without having to go and resize everything to fit the canvas?
Select all elements with ctrl+a and then group them with ctrl+g.
After that, create a rectangle with the area you need and use it as a clipping mask - https://documentation.designer.io/organizing-your-designs/clipping-masking/
Or export to PDF - which will crop/mask to canvas size automatically.