I built one a long time ago and as I remember it took quite a bit of lead up front, couldn’t now tell you how much. As I remember things I ended up making a larger battery, 4 sub C cells about 1100 mah to use up some of that weight. Now days I almost always use a 3000 mah battery for the same reason. Also as I remember the Viking you may want that extra time for flying, it flew well.

Personally I would not shorten the fuselage, but I like planes with long tails. Besides, does it really matter what the plane weighs (to a point).