Well, here's a stock, 17,000-mile unrestored '69 RR's trunk lid. SPD 2/12/69, St Louis.
'68-'69, there were 2 versions of the underside: a panel with cut-outs, and the full panel.
OP's car has base interior but Decor Group B-pillar caps. Those caps were available separately, but that's extremely rare.
I've seen the cracking mentioned on 1 or 2 HT B-pillars, but not on Coupes.
What I've seen of the subject car so far indicates a past incorrect restoration, and likely some major repairs early in its life.
I'm not buying special bodywork by the factory; I don't recall seeing a similar car in any of the early road tests or the traveling caravan Plymouth had.