Dear typographers and typophiles

I am writing a thesis, and am using Indesign as publisher after quitting latex, but I am constantly unsatisfied with the proportions on the A4 paper, which is the mandatory form. I am trying to apply the typographical principles, but especially in this format the rule about 66 character as the ideal, and 75 character as the maximum per line is very difficult to arrive at, unless you have very broad margins, and some large letters, which looks a little unprofessional. I have seen some solutions in journals where they use two columns, but that is probably to unorthodox for many professors, (who are used to see good layout in journals but bad layout by their students).

Is there someone who could help? Especially with the priorities: Which elements should come first, and how can you make a single column A4 thesis look good?

Best regards.
Jon