I'm with Alex - look at a quality kevlar canoe in the 16' range.
Something relatively straight-keeled that you could hang a side-mount
motor from. You should be able to find something at or under 50lbs,
which would facilitate getting it on and off the motorhome.

The sail rig is another matter; you are asking a lot of one boat in
wanting it lightweight, motor-able, sailable and easily stored. Any
boat that is equally amenable to paddling, motoring and sailing is
likely to be such a compromise design that it won't do any of them
very well.

I'd suggest first prioritizing your desires and realistically
anticipated uses for the boat and eliminating the one facet least
needed.