I'm good with far stronger at the cost of some weight. It's going to be so light that it just might be to slow and fly below the sub-critical Reynolds Number anyway, which would mean I would have to put lead on it to make it fly faster. My estimated AUW with battery is 800-900g, which is quite light for a 2.5m wingspan. The main spar for the first 20cm out from the centre will be the wing joining mech, the next 42.5cm will be an "I" beam, and the last 62.5cm to the wingtip will be a simple strip of balsa, like
my current build. Do you think that will be strong enough? Also, I'm really keen on aerodynamics, and learnt about a wingtip device called a whitcomb winglet from a book I borrowed from the library. I am planning on having a removable winglet system on the plane so I can experiment with whitcomb winglets and other wingtip devices.
By the way, here is a top view of the plane: