Check out your local T class association, then ITA if you don`t get any help there. Problem is that most plans for T will be old plans which might produce heavy boats by today`s standards. Could also check out the building plans for the Mosquito, then scale all materials up by 1.25, ie from 16ft to 20ft. so 4mm ply would become 5mm (have to use 6mm, don`t think 5mm is available.) Could build hulls to 25-30kg each, how does this compare to epoxy boats / class rules. Depends on how tight class rules are about internals on wooden boats. If interested, contact Tim Mozzie on Forum Database for more info in Auz.

Cheers
Steve