Two separate sleeping areas and a dedicated toilet compartment pretty much puts you into the 16' and larger class, and tongue weight will be your problem. As I mentioned on an earlier thread, Outbacks are limited to 200 pounds hitch weight. Most 16'ers will typically carry 240-275 pounds on the hitch. Some will come pretty close to your overall trailer weight limit as well.
I think your best bet is to stick with your original plan: a 13' Scamp
or similar. That includes Scamp, Casita
, and a host of other less-common vintage 13'ers. Some newer models do have a toilet compartment or even a full wet bath, but you'll be giving up the second sleeping area. If you choose the front bunk version, there is a porta-potty storage compartment under the front bunk.
I agree that it's hard to decide without seeing some in person. You have missed the rally
season for 2015, which is a great way to see a lot of trailers in one place. You could post a request here. You might find a member or two in your area willing to let you have a look. You could also contact the sales department at Scamp. They keep a file of owners willing to demo their trailers to potential buyers.