You're right -- Wharton has one of the most condensed applications of all of the top schools. I usually advise clients to ensure the details that won't fit in to the app are covered on their resume. In fact, for this very reason you may need a slightly different version of your resume for each school--usually with only the "personal/activities/additional" section changing across them. I have clients widen margins and lessen white space to get things to fit in. The MBA application resume is not about the document looking pretty, it's about communication as much important information as you can within one page and ideally telling a story about your career and your achievements outside of work.
Hope that helps!