Drop tanks would help to some extent but the thing is so small there's really not much room for more fuel. You could strip all the armour off of it as well as maybe two of the 20mm guns.
Yeah, you right. I try to make comparisons with other fighters, P-47, F6F or N1K Rex. P-47 is similar to size and weight, also engine has almost identic power. Maybe if change position of one pair 20 mm to the engine cowling we can make some room for more fuel tanks. Also striping armour ? I don't know, for me it's not a good idea.
One more thing, drop tanks in carrier operation. Any fighter in WWII us that ?