I've been looking for ways to travel from Ha Tien to Kep. Most of the information suggests motobikes (which sound high risk) or busses, which don't go until noon, and I was hoping to get away earlier than that. Are there other options, such as taxis or tuk tuks? I don't mind getting one to the border, and then another on the other side if necesary.
The Minibus from the Oasisbar in Ha Tien to Kampot via Kep leaves at noon as I mention in this answer. Though the motorbike taxis leave whenever you want. And yes it is not as safe as in a car. Though the driver can take your backpack between his legs in front of him like shown in the picture.
So you either take a little risk or get the minivan at noon. :-) I took a motorbike taxi quite a few times and kinda like it.