At those speeds, I wouldn't worry about a full-face helmet. Those are completely ordinary cycling speeds for a road cycling enthusiast. Your primary risk is probably rear and side impacts. Your body is really good at instinctively protecting the head, so you should worry more about surprise impacts, like t-bones and rear-ending.
I don't know what your helmet looks like, but modern cycling helmets have migrated toward a longer back side for better rear impact protection.
For what it's worth, one of the reasons that my motorcycle has a big top box and aluminum panniers is simply to store my gear when I get to my destination. Thieves suck and if something can be stolen, someone will steal it.
At those speeds, I wouldn't worry about a full-face helmet. Those are completely ordinary cycling speeds for a road cycling enthusiast. Your primary risk is probably rear and side impacts. Your body is really good at instinctively protecting the head, so you should worry more about surprise impacts, like t-bones and rear-ending.
I don't know what your helmet looks like, but modern cycling helmets have migrated toward a longer back side for better rear impact protection.
For what it's worth, one of the reasons that my motorcycle has a big top box and aluminum panniers is simply to store my gear when I get to my destination. Thieves suck and if something can be stolen, someone will steal it.