Daniel,
Just had a look at the Midwest Fantail and it was 19" long. Vic Smeed's River Princess is a 24" long open steam launch. The plan gives construction details for a clinker built hull using thin plywood (or other). The plan was presented as a free plan in the April 1989 edition of Model Boats magazine and never made commercially available. The model is a smaller, modified version of the 35" River Queen which is available from Sarik.
If this design would be of interest, message your email and I will send the magazine article and plans. Admittedly there is more work involved than the Fantail, but a lovely little model could be achieved.
Tony