Mike_Marra
Here is the current versions of the skyraider:
http://www.skyraiderllc.com/aircraft.htmand there are quite a few skyraider videos on YouTube.
A two seat version would be a light sport plane and not an ultralight. A light sport would need an N-number, the pilot would have to have the two year flight review, and the aircraft would have to have an annual condition inspection, and the taxing people would also be involved. An ultralight on the other hand would avoid all of these (at least in the official arena.)
There are some advantages to an ultralight. Here is just one oddity. An aircraft that flies under the usually 30 mile transponder veil of a class B airport has to have a transponder. But a true ultralight does not.