All of the above plus: Check out servo trays in the fuselage, tank mounting and hold downs, pushrods, fittings, etc. Changing materials and judicious use of lightening holes can shed weight. Moving things around to change CG can allow dumping of ballast whose only funtion is to balance the plane (and make it heavier). It's amazing how much can come out of a plane -- a few grams here and there add up.

Good luck with it!
Tom