I had a similar problem a couple of years back, when I started working as a 'student-teacher' in the university. I was supposed to teach a class that I had just recently passed myself. I was a bid worried but my teacher told me to take it easy. No matter what would happen - I would have the benefit of having done the whole course including the final bit where all the little things would come together and form a whole. I believe the same thing would happen in Aikido. No matter how old these people are or how experienced they might be in other MA's you will allways be the one there having the most experience in excactly what you teach.
As long as you don't try to pass yourself as a 'Master' they will probably respect you for your five years of practice and learn as much as possible from you. Be humble and do your best. No one should expect anything else.