We were actually prevented by the USFWS from performing winter hibernacula counts for fear that we humans might spread Covid to bats, whose immune system practically shuts down during hibernation, until it was determined that this isn't possible.
Besides, the bats which are primarily killed by wind turbines are not cave-roosting bats, but high-flying tree bats. Bats either have a strategy of hibernation or migration, and it is these larger migratory tree bats which fall prey to turbines.
Echo-reflective surfaces wouldn't make a difference. Bats aren't killed by colliding with turbine blades, they are killed by barotrauma when flying NEAR the high-velocity low-pressure turbine blades when they try to investigate the large, moving, novel objects. I repeat, the most effective way to prevent bat deaths at wind farms is to curtail (brake) turbine blades during low-wind conditions; a 25-gram bat doesn't fly in high winds, and turbines are least efficient in low winds.
Source: I perform bat echolocation surveys, including on wind farm sites.