I would pick FR4 for this job.  I select my FR4 Tgs by layer count not on final product environment.  If this were a 1 to 6 or 8 layer board or had nice annular ring, I would go 140 Tg.  It is more robust in elevated temps over long periods.  Based on operating temps don't exceed 125 C.  If you are doing a lot of bare board prebaking I would be cautious on surface finish selection.  I am not an advocate of prebakes over two to three hours.

Boston Brad