Bevo there hasn't been much said about any RP composites on the B2 but Schwartz said when talking about the B2 replacement come 2025..
"While the 20 B-2s in service are capable aircraft, their stealth technology is “80s vintage“ The reality is that the B-2 over time will become less survivable in contested airspace,
Do you think that the Chinese have established one of the world’s best air defense environments in their eastern provinces just to invest their national treasure — or, for that matter, that the Iranians have established integrated air defenses around certain locations in their country?”