Yeah, pre-mapping items via an import script is not ideal, but sometimes it's the best option. Sounds like that's the case here. Maybe others will chime in with other ideas.
Adjusting column size in TDATASEG_T and TDATASEG would work also although it is not supported and you would have to check if size is changed after applying patched.
Regarding mappings, you would probably have to adjust TDATAMAP, TDATAMAP_T, and TDATAMASEG...so yes, I think using import script would be a good option .-)
PS. it's first time i see such members...
Try opening a SR with Oracle and see if making changes to tables size is supported. I am sure they will say not but also can open ER