I use the RS #910-4925 counters on my cams (you really need to count to 999,999??). I have the cams set up so that I can switch between photo & counter and counter only. The counter alone is nice if you just want "traffic" data, but it does not tell event times. On one of my cams I use a HOBO 'event' data logger. Hooks up to the same jack as the RS counter. Kind of pricey, but it's cool to fiddle with the data on the computer.
You could always add in a cam later when you get one. Just use a housing big enough to fit a cam in.