Folks ran a fishing camp for three summers starting when I was 10. Flew in on skis and out on floats from lak la ronge to sportsmans lodge on macintosh lake in Saskatchewan. It was either a C 180, D beaver, N Norseman , or D otter. Been in all of 'em, can't remember which one was first.
Why the two wing limit? I personally don't see how my latest (brain fart) could possibly be constructed simply, but tomorrows another day.
A straight wing version would be easier to build and would have to be stretched from it's current 15' x 16' to add a passenger.
Seems like there are lots of choices for engines (Aerodyne Systems Vector - Wikipedia) but with a vne of 55mph... Is there an EAA chapter or ultralight hangout in your area? There's a search button at the top of the page that's pretty useful and sometimes you might get a straight answer to a...
Just so's you know... There's a few of us on here that wouldn't sign onto facebook even if they could find their password. It seems there aught to be some way to modify your settings where anyone could view without signing in. Good luck with that too.