Hi Jonah - I have attached here a MergeOBJ.exe utility - you can run this and it will pop up a file dialog and ask you to pick the .obj file. It will then edit the .obj file to remove the grouping and object label directives so it should appear as one single mesh object.

It seems like this might do the trick for you...

Let me know if you run into any problems and I can try to figure out a different way instead.

EDIT: removed the attachment and moved it to here:
http://moi3d.com/download/MergeOBJ.zip

- Michael