Luban is a program designed specifically for cutting large parts and providing alignment/connection pins.
Slicers such as OrcaSlicer have cutting built in.
Blender will let you cut in better and more complex paths that follow geometry lines rather than simple planar cuts.
Or... a print farm such as my own Starbase3d.etsy.com with big printers could print your large pieces whole and seamless so they retain their strength and eliminate your seaming work.