Billet knuckle vs stock knuckle
Stock knuckle with wheel bearing weighs 14#.
Billet knuckle with wheel bearing weighs 19#.
Bare billet knuckle weighs 13#.
We kinda knew this up front but after seeing them in person compared to the stock knuckles, aluminum would almost certainly be strong enough with this boxed design. Would require steel sleeves for the strut bolts and long bolt but the machining would go a lot faster.
The brakes will probably be heavier than stock and CV axle will definitely be heavier but I think a ~10# unsprung weight increase per rear corner will be worth it.