I have a possible strategy that might have some utility in others. While I would not consider myself a maladaptive daydreamer, I definitely have used daydreaming as a mild tool to escape bad situations, and still do and I would hazard I do so a lot more than most people typically do. What I have been doing though is writing down and fleshing out many of these daydreams. One way to really channel it is to engage in worldbuilding (see the wikipage for it for more detail). I have found it to be enormously theraputic, and I have been working on my main project for a few years now and continue to do so.

So, in my opinion one thing that might help excessive daydreamers is to try writing down - and taking it a little further and expanding upon - those daydreams!