Hi Slim, nice project! I agree that this plane will fly OK with RC gear, it should weigh less than 10 ozs to be a great flyer. A couple of tips for dealing with Guillows kits:
metal and emory fingernail files are good for detailing those notches and getting the parts to line up. A piece of spar wood with a strip of sandpaper glued to it works nice in the spar notches. The other tip is to sand the sheets of parts on both sides with 120 before breaking the pieces out. I can see that you already got those parts out OK though
It is not possible to stress enough how little glue is needed to match the strength of the design. Once the plane is covered with a lightweight covering, you will be amazed by how strong it is.
Thin balsa stringers, spars and longerons are too brittle for normal handling, it is no sweat to change them out to spruce or basswood