Tim,
They are symetrical.
You could always dig up a set of plans for a Farrier Trailer Tri 680 (22ft) and just build the centre hull or better still build the lot. The amas on those were a very simple shape and would be pretty simple to build. I have a friend with a 720 and he and his family get a lot of use from it. Although his later designs are much faster. Having a boat that you can sleep on and rig in 20 mins would be a great family boat. I know you have a lake house so the rigging may not be an issue but it may open up other options.

Regards,
Phill

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!