Yep, it's even got a name, Maui Nui and included Kaho‘olawe as well (and some bits that are no longer islands). The general concept has been around for a while (e.g., Stearns & Macdonald, 1942) and there's been a variety of efforts to "reconstruct" what this island would have looked like (e.g., Price & Fisk, 2004). In detail, the Price and Fisk reconstruction suggests that Maui Nui at its maximum extent was actually larger than the "Big" Island is today.