Since it is so close to the holiday I would send an email. I would be very upfront with your concern that your inability to visit the campus may be seen as a lack of interest. Ask if it would be possible to sent up a phone interview. I work have a teacher or parent look it over and give you feedback. But be yourself - the admission counselors love working with high school students. Your letter should not sound like an adult wrote it, But be honest with your concern - it is valid. Let them know why you are interested in Lehigh! Just keep in mind they like kids who like Lehigh!. You already have a lot in common!!! They have those jobs because they like working with high school students. Keep us posted!!!