I am looking for multi-purpose multihull with some special
characteristics:

-Low cost (less than $5000) to build (or buy second hand if such a
design exists)

-For lagoon use only

-As large as possible, it must have a 'yacht' feeling in terms of
stability, so fairly deep hulls, up to maybe 40 feet long

-No cabin or sleeping space required, just a trampoline or plywood deck
structure on top of two glassfibre hulls

-No rigging required (this is where the expense normally is), i imagine
using an outboard motor to get upwind, and a kite to get downwind
(see here for my experiments with this
http://www.beachbreaks.co.za/hobie-kite1.aspx )

Do you know of any suitable designs which may exist?

Thanks
Matthew