No formers needed... just re-glue one of the knockouts back in on the right side of the fuse cut your opening and add a small amount of light ply where the sevro screws are to give them a little bite. My last SE had this same mod with just an OS50SX up front and it balanced right on the nuts with the battery under the fuel tank. If you came out "very tail heavy" without aft mounted servos... I think I'd be looking at how much glue was used etc. Not to mention this plane has a pretty wide cg range anyway. just my .02

Look at my thread and you'll see the mod... again this is the second SE I've done this exact same mod to. The first one I had for 3-4 years and it flew great... until... well let's not talk about that. lol

http://www.rcuniverse.com/forum/m_5239448/tm.htm