First, you REALLY ought to try and get at least a swamp cooler to help even out your temps. Google it. Very cheap and easy to use.
That temp range isn't terrible, but the temperature inside the fermenter can be 5 degree or possibly more, which can be higher than you really want.
Which yeast did you use?
Next, Wit uses a good amount of wheat, so it may create more krausen than a lot of other styles and it can stay around longer too. Don't worry about it. Just check the gravity and see if it's done. If the gravity is where it ought to be and is stable, then you can rack the beer to a bottling bucket, or into your keg, from UNDER THE KRAUSEN.
It will be fine. The nice thing about a Witbier is that they aren't supposed to be clear anyway! A little krausen won't hurt it. Just be sure it's done. Bottling too early can cause bottle bombs.