I think you make some good points. I am only 2 months into maintenance and so far it's as much work. I am not trying to lose weight so I am actually exercising a bit less, eating about the same. For me I think both things are key, exercise and diet. My diet is for life because of diabetes so I feel like as long as I stay focused on that it will help me control my food. I do think I need to stay relatively active. I do notice I walk less now than I used to but my goal is never to walk less than 3 times a week. So far it's worked.
I had a worry moment about 2 weeks ago. I went on a short trip and it's just like you said, by design you have to eat out more. You can't cook on a vacation. And you try to make the best choices but the best choices aren't as cheap as some not so good choices. I gained maybe 7-10 pounds maybe, clearly that was due to some water retention cause I also wasn't having my required daily water. Anyway, the point is I got right back on my way of eating when I got home and I am now once again at my lowest weight ever and that's only with 3-4 days of walking a week. I did go right back to walking though, can't forget either one.
I think already that I am feeling that maintenance is all about controlling spikes, if you will. You watch that scale daily and get on top of situations as soon as you can. For me this almost always involves a trip. I am going to spend about 2 months away from home this summer and I am very worried about it but I am already making a plan on how to keep active and not eat out so much.
I do feel that keeping the weight off needs as much vigilance as losing it. Sadly that's the way of life for the reduced obese. We can't let out guard down.