Edgar, tks! Good tip, I will try it.

Here my last updates, tanks are fitted with a bracket as earlier in this thread. Had to ream out the holes where the tank fittings stick through. Both to the inboard and top side.
Top tank fitting was too tight, had to file back the flanges of the fuse and engine bay cover.
Plus pic of the bottom of engine bay where pneumatic tubes run and electrics from the wing, YES, I like VELCRO tape!
Note the high tech balsa blocks , they serve as bottom rests for the tanks.
When installing them finally I will put a dab of silicon kit on those, plus the side that almost contacts the fuse sides.