Try the Micro Z72 antenna from Balsa Products. These are 3" long and super lightweight at .7 grams. Range is about 90% of normal, plenty for 1/2A stuff. You can put them just about anywhere on the plane. I'm using one in my Gopher electric plane. It is inside the fuse right next to the servos and servo leads and works fine. Todd's Models also carries the M72-L and M72-I antennas - they are base loaded and also very small and light.