Hi Capitana Chani!
I know that at least JANMOR is/was exporting a lot of motorboats to U.S. Hundreds a year some time ago. Delphia probably has its representative in U.S., but I'm not so sure about is. Anyway, why not give a try to contact them?
Trailer cruiser concept
here is somewhat different than in U.S.
They are not simple weekenders, but real boats, wih small, but proper galleys, WC comparments, good sleeping, good locker space and so on. On such a boat You can live aboard much better than in camper car. And most are semi-custom, so You can get what You want.
Some pages are in Polish only, but You can always use contact page (normally "Kontakt" on the page) and send e-mail for details.
All links I posted regard well proven and solid boats. My own choices are Janmor. Delphia, Maxus, Phobos and Aquatic (Maxus probably as a first), but others are also nice boats.
Have a nice browsing