Seeing as you need a bit of up trim you may be able to get away with just a bit more weight. Although I bet there was a fair amount of weight with all the tape and cardboard, sounds like your going to be grinding off some paint and laminating some 1/32 balsa to build up the fin. (I would try 3 layers extending two if them back onto the existing fin and then sanding them to give you a nice airfoil shape for the fin.)
From both the weather and news sounds like it been pretty gray and wet out there for awhile now, must have been nice to see some sun.
Feel a bit like a gremlin going bright light, bright light, did ya?