Long time lurker here from Ron's 2012 cycle.
Reddit is actually pretty supportive towards Rand, more so than Trump/Cruz. About half the people in r/politics say things like, "he is the smartest in the GOP field..I just wish his economics were different but I love his foreign policy" while the other half just think he is completely irrelevant and nothing like his father (who btw was loved on reddit nearly as much as Bernie is now.)
Obviously Rand won't be able to answer all the questions asked so I think it is important to have intellectual discussion (as much as possible) with the Sanders supporters when the inevitable questions about the environment, top 1%, healthcare, etc. pop up. AMA's with prominent politicians get tons of views so this is a great opportunity for Rand and his supporters to spread the message of liberty. So if you don't have a reddit account its worthwhile to make one. All it requires is an email account.