When seeing stats, a middle guard relay in a datacenter looks like ok ;) Some months are needed to have a good consensus score, then some Terabits will be routed every months ;) Here is a graph since the beginning on this relay...
yearly graph
Not trying to dissuade you from running a bridge, just pointing out that that the bandwidth you want to donate to the Tor network may not be utilized. In contrast, I haven't seen a mature middle node that went unused.