I'm just finishing my assembly of my second Avistar and have just completed the balancing. My battery ended up 6.25 behind the rear wing dowel former. Just behind former F5. By getting the battery back there, I only had to add .77 ounce at the tail to bring it to balance. I'm using a GMS 47. If I ever would do this again, I'd be tempted to mount the rudder and elevator servos on the outside of the rear fuselage. Or maybe even better, shorten the nose portion. But it comes down to, "hey TOM!, It's just an Avistar!". Have fun with yours, They're meant to be fun.