Ethical dilemma

I’m in the middle of a big refactoring job for my work project. I’m basically restructuring all the classes that make database calls so that they use connection pooling with a per-thread “DatabaseHandle” that caches PreparedStatements. It’s a big job, and it’s going to take a LOT of time and concentration, which means that home is a far better environment to work on it than at work. The problem and dilemma comes because I was on a roll when I hit 40 hours for the week. I’m not allowed to bill more than 40 hours, and I’m sure as hell not going to do it for free. Nor can I work from home without prior approval and that’s not easy to get.

So my question is, do I quit now and hope I can quickly get back in the groove on Monday morning, or do I work on it this weekend and then when I’m done spend an equivalent amount of time at my desk at work working on personal projects, like my photoshop stuff? I’m thinking it’s probably safest, although nowhere near as productive, to shut down Eclipse right now and don’t look at it until Monday morning.