A driver who "doesn't see" a bike hauling a trailer is just as likely to "not see" a bike not pulling a trailer.
Gotta disagree on the hybrid - get a cyclocross-type bike. Basically, anything a hybrid can do, a cyclocross bike will do better. And there's no reason you can't set up a cyclocross bike so you're in a more upright position. Drop bars don't mean you have to set up the bike for actual road racing.
I'd definitely try to get a steel-framed bike for hauling a trailer, though.