How much endurance work is good for maintainance would most likely depend on the volume the athlete did during general prep. Some athletes need to come off that peak volume in order to race often and well. Some athletes maintain their usual volume all through the racing season and merely adjust the intensity or the volume of intensity. As a coach, those are numbers that you'll want to keep close watch on and adjust as needed. My concern as an athlete during the peak phase was that it was easy for me to put on uneeded weight at that point so I wouldn't drop too low on volume for too long for that fact. My thought is that is all depends on what your goal race(s) are going to be. If you want to run alot of good races over a fairly lengthy stretch of time then you don't want to drop too low. If you have one or two key meets then you can plan about a 3-4 week period in which you'll really drop down and just try to keep the "snap" in your athletes' legs.
AFA speed endurance goes, I would either have a meet or two in which you run the open 400 and/or a 4 x 400 leg or have one session, but place it as early in the week as you can-probably Monday or Tuesday if your races are on Saturday
It wouldn't be bad if you could arrange a meet early in the week to run one of those events because it's just more effective. If the meet you are wanting to peak for has prelims, then you'll need to prepare for that. I like to schedule what in the GP phase would have been speed development on Monday and then come back with speed endurance or the less intense pace work (current race pace or even a bit slower over 2-300 meter segments) on Tuesday. The rest of the week can be medium paced and short-medium length distance runs. The key is to maintain and let the races put that little extra bit of sharpness on the athlete.
It might not even be a bad idea to do some stuff off the track as well. One workout I like to have people do during a peak phase are some gently sloped downhills on a grassy area. They force you to speed up your stride length at a point in the year in which you ought to be able to handle it. With that type of running in their mind, you can transfer that to some mental imagery they can use in the race. For example, as you are talking about the different parts of the race, you could say-just imagine you are running down the _______ hills you've done in training and that cue should help them connect with an experience they are familiar with and feel good about.
You can usually get to peak form after anywhere from 6-8 800 meter races so when you are plotting a racing scheme keep that in mind and don't race the prime distance too often. Do some 1500's or at least some 1000 meter races and also get some 400's and maybe even some 600s (most likely during indoor or just do some time trials) in as well.
Another thought I had about speed endurance work is that I like to put more recovery in as the season goes on while leveling off on the intensity about 3-4 weeks from your most important race. Don't let the athlete leave it on the practice track late in the season because as the weather gets nicer, it's easy to do.
I hope you find this helpful