having no 'real world' experiences, i'd say that the feasibility studies are similar in many respects.
so you should be following your heinemann text.
would it make your assessment any better if it were verisimilitude (true to life)?
i'd recommend that you stick with the text, follow the guidelines as outlined in the text because that's what you'll be expected to do in the hsc, (and your teacher should be marking assignments to a set criteria, but i can see why you would want to be 'different' than the norm)
my advice is to stick to the conventional layout and structure;
(page 16, heinemann)
top of the page,
title page
contents
problem definition
requirement report
summary of investigation
alternative solutions
recommendations
project plan
appendix
if you do a very good (detailed) feasibility study,
you should hit the 30-50 mark easily (throw a lot of things into your alternative solutions as well as having a few gantt charts and some surveys/data collected during the preliminary investigation to throw into your appendix)
g'luck