I use bigger batteries. If you are still in the hovering, figure 8s stages and not doing any 3D flying just go with bigger batteries. That way you don't have to worry about angled trays, extenders or anything else. I put in a bit of styrofoam at the back of the battery tray to position my batteries everytime I put in a new battery for flying. I simply push in a new battery until it touches the foam, strap in down and fly. I use my stock batteries for setups and I have 6 2200 - 30A batteries for flying.. all the same size. So I found the CG for one, setup that and all the others are set to go as well. cheap and easy

happy fly'n