This plane takes time to build....as you are finding out.

My suggestions for a second wing are to leave on the wing blocks and extend them past the ailerons, cut the ailerons short of the wingtips to prevent flutter, make the ailerons bigger for better roll rates, and no dihedral. The Kavalier is known to have aileron flutter at high speeds anyway, so be sure to seal the aileron gaps when covering.

I was considering making the rudder bigger today when I was looking the model over. It has good authority now, but maybe a larger area would be nicer. Maybe not.

I would suggest that you place the main gear about a half to full inch back from the location shown on the plans. This plane will rock back on the tail easily. It always seems that the plane is tail heavy when on the ground. Also, this is a good time to cut pine blocks for using 1/4x20 nylon bolts to hold on the gear. I did that when building mine. It is much better than just using wood screws.Tap them the same way you need to tap the wing blocks...unless you are using the rubber band method.

What engine will you use? I used a Saito .56 with a 12x6 APC prop. I use a 2 3/4" foam nose wheel and 3" main wheels. The plane was impossible to land without bouncing since the wheels were almost the same diameter. I raised the main gear with a covered 1/4 balsa block and it lands fine now. Prop clearance is okay, not great, but okay.