Now this will be complicated w/o BPDUs over the fiber.
As you have routers on both ends, you could try to run a PPPoE tunnel through the fiber and terminate this tunnel on your bridges on both ends.
(means: remove the SFP interface from the bridge, create PPPoE server & client on the fiber interfaces and add those to the bridges). This should enable you to run RSTP over the fiber.
When using RSTP, bare in mind that bridges with higher priorities are disabling downlink ports coming in with lower priority, not local ports having lower priority. So give the fiber port a low port priority on the router with the lower priority.
MTCNA, MTCUME, MTCWE
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There are two types of people: Those who can extrapolate from incomplete data