I’d recommend finding a good group to ride with to get comfortable riding in close proximity to others. It takes some practice to comfortably hold wheels without letting gaps form. You’ll gain far more sticking to someone else’s wheel than the little extra you’d get with clipons. Also, you should ensure you’ve optimized your position perhaps with a professional fitting.

If I couldn’t hang with any groups I’d just relax and just enjoy the day, and I certainly wouldn’t be riding 100 miles on the aerobars.