What if I made 2 Herons and then
: constructed a sailing rig with outriggers and trampoline and made them
: into a catamaran? A furling trampoline could keep that out of the way for
: paddling, yet deploy to provide a platform for standing/lying/moving
: around. This could be very cool! I’m very impressed with some of the
: sailing outriggers and tacking proas I’ve seen lately, (like the hydrofoil
: equipped Raptor, and the tacking proa Flaquita). This could be a great
: platform to experiment with. The Heron is probably not the ideal choice
: for sailing, she’s a bit light especially in the bow, maybe I could add
: tab foils at the shear bows to coax her over waves? The trampoline section
: would hold a mast, a rudder and a daggerboard (and maybe even a tent for
: camping) and the kayaks would be easily detachable by pulling the CF
: stiffened 2.5” aluminum tubes out of reinforced receivers in the hulls.

: So if any of you have heard about stuff like this, or you have a neat idea to
: contribute, or like me you get bluebrains and need some periodic mental
: masturbation: My big first questions so far- is the swiveling seat doable
: and does it need a big open cockpit? Does it cause instability
: (NightHerons are

It seems like even with a swivleling seat, you would still have to have room to move your knees and/or whole legs quite a bit to avoid rotating at the hip and spine area.
Your other ideas are all doable. Easy Rider kayask and canoes have many of the features you mention (hulls set up to join together, various sized outriggers and sail set ups.)
Verlon Kruger's ocean canoes were set up to be joined into a catamaran with aluminum tubes for rough water.
I put extra deck beams and mounting points on my Chesapeake 18 to mount cross bars on.
You can buy various drop in pedal/propeller units for inline leg propulsion with paddle manuvering in tight places.
You can buy the Hobie drop in unit for about $500 with their back and forth drive unit, it is quite efficient.
There used to be a place in Montana to get a stainless steel sealed 2:1 ratio pedal unit that can be used a number of ways.
There is a forward facing rowing unit made in New England area that can use legs and/or arms. Quite efficient too.
I've got three working models of forward facing rowing units I worked up. Since I made them, I found two similar ones on the web, one commercially made.
One interesting outrigger design just uses a plywood triangle on one cross piece (aka or ama, I can't keep them straight.) The plywood is angled 45 degrees back toward the boat, it cuts straight thru the water while sailing, provides down resistance as you lean toward it and upwards resistance as you lean away.
Search for "Trampofoil" for another good way to go forward by jumping up and down.
There is a fairly efficient elongated flexing fin/rudder that moves the kayak but only forward.
Build a double and find a not-too-bright but very strong second paddler who will work hard for brownies or other rewards as you ride.
Check the Human Powered Vehicle society's boat page for other ideas.

Randy