Duplex with LTR upstairs and STR downstairs. Potential problems?

[Palmer Thomas]

I own two duplexes in a small southern coastal town that are currently filled with long term tenants. The location of these properties make me think they might make very good short term rentals. To test the market, I was thinking of converting one unit to STR when one of the tenants moves out. This would lead to a duplex being split between long term and short term renters. What potential issues should I be concerned about? The units are 2/1s so I don't think I would get too many party crowds. The houses are well over a century old, so sound dampening between the units is non-existent. Has anyone tried this and run into any problems?