What about the 3W 24i? The Matt's use it in their 3W Xtra-fun. The plane is 1.9 m wingspan and 1.99 lenght(like the pattern planes), it weights 4.8-5.0 kg wich is ok for pattern rules. This model is designed for 3D but maybe it is possible to change the design for pattern flight, use the same engine and maintain the same weight. Note that they use it for 3D, so it should have plenty of power. This is the link:

http://www.matt-rc.li/englisch/index.htm

Just an idea,

Manu2604