I've built 11 of these planes used as club trainers...

Don't use dowels. There will be too much torque on the dowels and the extra length produces a high lever moment.

You can use hard wood if you maximize the contact area as much as possible.

On our club trainers I am using lowely DLE 20 engines. These engines are far TOO light for the plane, yet they power it adecuately for a trainer.

In the picture below you can see how I've moved the engine out much further, to both adjust the C.G. and to permit the use of heavy duty Fults struts in a tricycle configuration ( better for newbies ).

The fuel tank is in the aft position and I have a 4200mAh 9v LiFe pack behind the firewall to power the electronics as well as a 2200mAh 6.6v LiFe packs for the ignition.

Click image to enlarge