That's looking great. But you're right about having to keep the weight down. I did a semi-scale EIII as my first RC build and it ended up a lot heavier than a model like this should. The fuse, undercarriage, and tail feathers were as scale as I could make them at the time (about 6 years ago) but I used a non-scale fat airfoil wing (with ailerons).

The greatest challenge was trying to get the all the radio gear AND the fuel tank into the front 3" of the model! I ended up making a custom brass tank to fit over the servos.

I didn't really do any cockpit detailing, but I don't think the EIII had any "instrument panel" at all.