DRLane i'll share a few ideas beyond the basics you already mentioned.
since you'll be using a 1/2 cage, i presume carbon doors are off the table. you can still take 3lbs out of the doors without reducing safety by losing the insulation and trimming some excess metal. another silly thing i've fantasized about is moving the driver's side door controller to the center console. this moves weight more inboard, potentially allows for less wires, and you get to ditch the passenger side window controller completely.
replace the rear window and rear quarters with lexan. i wouldn't touch the front windscreen for safety, and leave the sides alone, because they would have to be fixed.
https://www.plastics4performance.com...=126&model=191
move the lightweight battery to behind the passenger seat on the floor, and shorten the battery cable.
titanium nuts and bolts where applicable (its not cost effective, but none of this is).
scrape off all the adhesive sound deadening bonded to the body.
trim all interior tabs that are no longer used.
get rid of your hood and trunk hinges and the struts associated with them. use aerocatch latches instead. a pair of trunk struts weigh about a pound. the hinges weigh about 1.5 pounds each!
drill out the front radiator support. it looks like its plastic, but it has a metal core.
get rid of the windshield washer assembly, or run one wiper. (i'm currently working on lightening mine, its a long term project).
thin out the wiring harnesses to only keep what is necessary.
if you have a really lightweight exhaust, you don't need the side rear exhaust mounts. they weigh about 2.4 lbs.
burger tuning cowl filters.
what did i miss?