I've hit on one idea that's becoming more prominent in my mind. As I said before, the blue dress doesn't work and the loveheart doesn't work, which is a shame because being physical objects, they can be very emblematic and cinematic (just as important in a novel as on a screen, trust me).
But what about the sexy phone call, the one Dale's thinking about as a 19 year old crossing the bridge when it starts to fall? It plays a bigger part in Vicki's story anyway, forever anchoring her sexuality to her fears of the bridge.
During the Vicki being The Girl rewrite I've just expanded and explained that aspect ion the sequence when she's driving onto the bridge to reach Dale while he's in the hospital and finds herself back on the bridge with everything coming back to her.
It also explains how she wants him so much and gives into it, which to be honest might still be viewed as just the love interest falling into bed with the hero.
But it's one thing they'd both remember. Dale remembers it well because it's what he was thinking about when it all started. If I can think of a way she can mention it during the therapy session when they first sleep together, it can be the big reveal Dale realises and becomes convinced it's her.