The main suggestion I have is to add a second rear light. Unlike the headlight, the rear one can fail without you're even being aware of it for some time. The battery can fail, there could be a bad connection inside the light, the light mount may have failed letting the lamp fall off, etc. In this case you'd be especially vulnerable during the time before you become aware of the failure.

So redundancy in the form of a totally separate second light is especially important for a tail light. If there's no room on the seat post you should be able to attach a second light to your seat stay.