Zach, I have an old Santana Visa, '93...a bit newer than your bike. My old tandem was around a '90 Burley Duet. It had a Suzue rear hub with a bolt on axle. I had an old and light Campy 15mm (I think) alloy wrench that I carried with me. http://cgi.ebay.com/New-Campagnolo-P...item3f068181ec It looks like you already have a quick release on the Arai drum cable. Short of rebuilding your wheel with a quick release hub, you are stuck with the wrench. I always found that if I shifted to the small cog in the back, it made the on and off a bit easier. If you push on the little tab that retains the chain near the lower jockey wheel on the deraileur, you can pivot it out of the way without getting alot of grease on your hands. I don't know about the large socket, I seem to remember that a large pin wrench was needed to remove the brake from the hub.
Also, judging by the downtube shifters and lugged fork crown, I think that the bike might be a tad older. If you call Santana with the serial number, they can give you year it was built-not that it really matters.