They say former employers can only verify dates of employment

I don't know who "they" is, but this isn't true at all. Many large-scale employers are only willing to verify dates of employment, because they're scared of being pulled into a defamation lawsuit. But that's just an overabundance of caution from them. There's nothing to stop your former employer from responding to requests with "southphillyman typically visits the toilet every day between 11:20 and 11:40".