The one thing that could be annoying are not the one strength units landing on ports (as ports should be garrisoned in a game at this scale), but one strength units landing... not on ports!
In other words those units landing behind enemy lines, moving two hexes inland and cutting supply by, for example linking with armors that breached the line farther inland. Another similar example would be a battalion (more or less a 1 strength unit), or maybe two, cutting Italy in two.
Not sure yet if it is a serious problem, more games are required to be sure I would say. If indeed it is, maybe requiring a unit to be at least at 50% strength could be enough. No problem on my side with half a division doing that. After all 1 strength units can already do it even without landing, just by walking in a hole in the front as it will eventually happen in a crumbling front.

