I never saw Lighthouse in its heyday, it was in the reunion era, circa 1996, that I first caught them. Lucky you to catch them with Bob McBride et al. Still, they have the basic core -- Skip Prokop, Paul Hoffert, Ralph Cole and original trombonist Russ Little (now pushing 70).
The song isn't any of the three you mentioned, I'll leave it as a bit of a surprise
Okay, no bells and whistles, Char, sometimes less is more!