I really don't get why you don't just vpn, its sure not overkill. And allows you do other stuff other than just ssh in. I can vpn in from my phone, my desk at work via a proxy.. Click I have the vpn connection.
As I stated before if your going to allow ssh on the wan. I would look it down to only the region of the world your going to be coming from, and yes turn off password auth. If possible lock it down to your actual IPs or netblocks you will be coming from for remote admin. This is quite easy if your admin your own remote sites from say hq or your house, etc.
If you leave it open your going to not only get firewall noise of a hit, but log noise of them trying to log in even if you have just public key. If you want to reduce that noise then change the port - but this might be a limit to where you can access it from if they are not allowing for your non standard port outbound.
One of the nice things I like with openvpn is running it on 443 tcp which pretty much always open if there is internet access where your at.