Hi Mike,
I played around some more with using UDIM’s with RC and got it to work. I renamed my materials and textures to the UDIM naming convention.
Then I moved my 6 UV’s form 0 to 1 UV space to UDIM’s.
I imported it in to RC, textured, and exported the results. It worked as hoped.
I tried combining all the textures into one material and importing into RC, but got the message “A texture coordinate u or v is bigger than 1”, so it appears each UDIM has to have it’s own material in order to import into RC.
Here’s a link to the modo UDIM .obj:
http://www.digital-mapping.net/forums/CapturingReality/2018/modo_UDIM.zip