PS. so one easy way (well, maybe not easy on an already built airframe) to make certain you are OK is to add tail vertical stab area to compensate for the added nose area. The "volume" needs to stay the same. So if you add 10 square inches of side area to the nose (in front of the aero-center) and the new area's centroid is 10 inches in front of the aero-center, then you need to add the same amount of "volume" to the tail (100 in^3). Say the centroid of the added tail area is 5 inches aft of the aero-center than you need to add 100 in^3/5 in = 20 sq in. Therefore the new added tail volume is 5 in times 20 in sq = 100 in^3, same as was added to the nose!!!