I posted this video
on my FB page. I think this would be an ultimate day-hike.
36+ miles/3000' loss/gain at max 4500' altitude. The altitude change and altitude are easy, the distance and environment are epic. I camped there in '73, '98 and '02. Never in the hotel. First time there were no permits & naked hippie girls and it has deteriorated from there. This adventure avoids maltreatment of the burro/mule livestock.
This is how to experience Havasupai:
Get to Hualapai Hilltop with a camper-van (or cowboy-camp off the highway). Take daypacks and hit the trail at sunrise. Take lots of film or memory chips. Take extra litres of water and bury it at the bottom of the descent. No need for compass, as the helicopters fly due North/South. Post something at the Post Office. Only PO using mule transport in the USA. Buy ice cream at the Village a) because you can and b) a small cash injection into a poverty-stricken area. Swim at either or both of Havasupai and Mooney Falls - both ways. Take Tevas or equivalent for the many water crossings between Mooney and Beaver Falls (another good swim) and the Colorado. Long lens because you are likely to spot mountain sheep. Swim in the Colorado - but be aware that if you get too far out you get to body-surf the rapids ! Romp back uphill - the ice cream shop will probably be closed, though. At the bottom of the last (and only) big climb, dig up the water, refill your water bottles, get fully hydrated, offer water to other travelers & give yourself a big splash if it is still hot. In reality, midnight is more likely. Hit the top & camp or drive.
YMMV. Current permit requirements are more money & might not allow dayhikes as such.