Welding a strap thats a couple inches or what ever is need around the edge like Dave suggested looks like a pretty good idea. Would allow it to cool off and easy for maintence access.
Perhaps a pipe nipple cut as short as possible so as to only have a few threads left. Then welded on over and around the bearing. Then a pipe cap screwed on if your wanting complete coverage. This would allow you to access the bearing more easily if repairs become needed. May have to check somewhere besides a box store for a fitting large enough. Fabrication shop, commercial plumbing store or oil field supply house.