Detecting and dealing with bad word wrap (IMGUI)

I have a screen in my game with three buttons arranged along the bottom of the screen, using GUILayout. There is sufficient vertical space for the text to wrap onto multiple lines, but sometimes a piece of text contains a word that is wider than the button, so I get a line break within a word, which obviously looks bad.

My initial approach to fixing this has been to fix the width of each button to Screen.width / 3f, and then use CalcHeight to compare the height of the text on a single line to the height of the text when restricted to Screen.width / 3f. I then compare this to the word count of the text – if, for example, a piece of text with two words is going to wrap onto three lines, I reduce the font size and try again – see below:

 GUIContent content = new GUIContent(it.txt);
 int wordCount = it.txt.Count(ch => ch == ' ') + 1;
 float height1Line = buttonStyle.CalcHeight(content, 1e5f);
 float height, numLines;
 do
 {
     height = buttonStyle.CalcHeight(content, (float)Screen.width / 3f);
     numLines = height / height1Line;
     buttonStyle.fontSize--;
 }
 while (numLines > wordCount && buttonStyle.fontSize > 10);

There are two problems with this, as far as I can tell. First, fixing the button width at a third of the screen width means the third button ends up going slightly off the right-hand edge, because GUILayout puts a small gap between each button. Second, I still sometimes get line breaks in the middle of a word – I'm wondering whether GUILayout has a padding area between the edges of the button and the text area, so that the text doesn't go right up to the end of the button.

The first problem could be fixed by switching from GUILayout to GUI, but it's not clear how I should deal with the second problem, beyond just guessing how much padding there might be. Is there a better way? Does the new GUI have any tools to deal with this kind of problem?

Edit: I've solved problem 1 using GUIStyle.margin