i used to fly 6 on my trainer and never had a problem i think 3 really hold it and the other 3 gives me room for them to break?
or
do some kit bashing and mount a piece or wood with some 1/4 blind nuts on the frame and attach the wing this way and kick the rudder bands to the curb. Then install a 1/8 piece of lite ply on the wing side for the 1/4-20 nylon bolts.