Can anyone advise on small craft?

I regularly need to cross what is to all intents and purposes, a lake
of about 4 miles in each direction. I also need to venture along
inshore waters of the sea coast, in calm weather.

I need something that I can lift onto the top of my car,
single-handed, and portage single-handed from my car to the water. I
can usually park within 30 yards of the water. I guess the maximum
length of boat I can carry on my small car is about 16ft, and the
maximum beam about 36".

I've tried using a 14-foot 60-lb Canadian-style flat-bottom canoe,
which serves well in calm conditions. I like it because I can stow a
lot of gear in it, or take another person along.

Unfortunately, the canoe feels unsafe when encountering the waves
higher than about 18", even when encountered head-on. The waves caused
by power boats are a particular hazard. I haven't been swamped yet,
but I feel it's been a close call on several occasions.

A sea kayak would be another option. However, I'm not keen on kayaks.
The storage space is much more limited, and I'd really like a boat
that I can attach a small outboard motor to. I find kayaks
uncomfortable too. I'm no youngster, so getting in and out of them is
a chore for me, and I like a boat that allows me to shift postition on
a long trip. And, unless it's a two-seater, I can't take another
person on board.

Is there any other kind of small boat that might serve my needs?

Thank you,

Al Deveron