Anyone has recommendation on IV like this one? One that hovers on non-porn and porn. Most gravure are too "mild" for me if that makes sense.
Err...depends on what you are looking for, and what you consider to be 'hovering the line'
Titles by キャメロンG (CMG) have outfits that are even more daring than this, but no 'simulated sex' scenes.
Kingdom (KIDM) also goes very far to the point of testing censors with their dark scenes, but they don't seem fond of 'simulated sex' either although some titles might have it.
Many AV girls actually do gravure works under different labels like Rebecca (REBDB, GSHRB), Air Control (OAE), Bagus (BAGDB), Garden (GAOR)...probably a few others but those are what comes to mind at the moment. They will definitely have simulated sex scenes but most would be fully naked which may or may not be too porn-ish.
And frankly, Tsubasa herself has already been doing this since pretty much the start of her career, starting from TSDV-41471 (not exactly her first, but that was never available online so...) which had an extremely brief simulated sex scene. Well, she's lying there with her bikini top on and lotion being drizzled on her, but she's also making that back-and-forth motion and you know what that implies.
Her next release (MMR-218) is when things start to escalate and is about as 'ero' as this very release. This is just unusual for WAN which is owned by Imouto but there's actually nothing here that Tsubasa herself has not done before. WAN just happens to have higher production values.
SBVD-0176 has a very unusual scene for a gravure video. You get to briefly see a silhouette of her giving a guy blowjob.