Last time I when to HI, I flew at the end of each day... GVA - LHR - LAX - KOA in J/F
The key was to arrive on the evening flight into LAX at about 19:00 was in bed in my airport hotel by 20:30
The next day we had the morning in LA before the evening (about 17:00) flight to KOA, arriving at hotel at about 20:30 local time again.
A walk alone Ali'i drive to stretch the legs was just the trick before bed.
The night in a bed in LAX made the flight to HI, even in a narrow body recliner, more than acceptable. My 70yo mother also kept up with the pace.