There are some theme oriented SS1k rides http://www.ironbutt.com/themerides/. I don't think "approved" is the right word here. You can ride any 1k that suits you as long as it meets the requirements of the rules. So I suspect the thing for you to do is play with google maps and create your own route. A few simple pointers: Keep the route simple. Try to incorporate higher speed roads. Plan on getting DBR (dated business receipts) at each change in direction or turn around point. Consider weather or not you will hit any major cities during rush hour.
Delmarva is a small area. If you want to try to do a 1k within Delmarva you should discuss your plan with IBA management. Ira can help. Otherwise you have a few options: North then west PA turnpike or I 68. Over the bay bridge then south on I95 or west on I 66 to I 81 south. Or go south to Norfolk and then I 64 west or I 95 south. Obviously, I'd avoid I 95 North due to hundreds of miles of congestion. Several of those options lend themselves to "out and back" 1k rides.
I also live on delmarva and I would have to say that a ss on the Peninsula would be hard. I just recently did a ss marathon to new hapshire and back in 22.5 hours as part of the cycle gear go ride challenge. As such I recommend that you stick to the major highways for your first time.