Alex, I knew a guy who made practically everything out of junk and I've never done it, he said he made a cheap trail timer out of a cheap digital watch using the stop watch feature. Glued the watch on a piece of wood he would screw to the tree, screwed a spring to the wood from a broken ball point pen or some such in such a fashion that it would push the stop button when extended, rigged a cotter pin to string to pull the pin and extend the spring. He'd check it every day, starting the stopwatch when he left and the string would tell him the time it stopped. Backtrack from the time you started the stopwatch and voila. I'm sure he fiddled with it endlessly to get it to work but once he did, I'll bet he only had a couple of bucks (if that) in the parts. He had a cool beard like you so it'll probably work for you too. :D I gots no other idys but that one for the moment.