Personally? Bottom-line-up-front? No, it's not too high of expectations. You are a highly skilled individual who can set your terms of employment. If only working 40-45 hours/week max is something that's very important to you, then it is not too much to ask.

Hell, I personally always tell my new bosses that (understanding that occasionally shit happens and I may have to work extra, and absolutely will) I refuse to regularly work more than 40 hours. If that is something they can't handle, I don't want to work for them.

Working no more than 40 hours is extremely important to me, but that does mean I have to compromise in other areas in order to get a job. I have never had any complaints from management though, because their job should be making sure that we can all accomplish ours.