Moving to altitude for last 4 weeks of marathon training - need advice

Go slower, that's about it. Should do wonders for your marathon.

What is the elevation where you're moving. You might find that you'll only need to slow down a bit during work outs. I'd say just go about it normally and run slower when you feel like it. Too bad you couldn't move out sooner and get the benefits of the elevation.

I'm moving from sea level to ~5000 ft. Moving out sooner would definitely be helpful but at this point I'm just trying not to overdo things rather than take advantage of the altitude.

Is one month long enough to get a benefit from altitude?

yeah just go slower

Yes.

4 weeks is not long enough to give you any benefit. What is can do is lower your confidence if you are too hung up on the watch. Focus more on effort and make sure you are getting plenty of sleep/recovery.