@Jason Carignan,
I had a similar post about processing and Mark Blacklin was enormously helpful:
https://community.pix4d.com/t/6220-DXF-Contour-Lines-misaligned-in-AutoCAD-Civil
It seems there is a size limit of 500MB for orthos so you may want to bite the bullet and get a copy of Global Mapper or similar.
Good luck!