I've done it twice. Goodness though, that was roughly 20 years ago now.
My father and I did South to North in two days, and a few days later I went North to South in one morning.
Dad and I booked a cabin in Phantom Ranch for the overnight. This meant we only had to pack a change of hiking clothes and a few toiletries. The cabin provided bed sheets and two meals. These are sold out within hours of opening so you're typically booking a year in advance.
We hiked down the South Kaibab trail which is shorter, but has no water along the route, then obviously out of the canyon via the North Kaibab. Mom and a cousin drove around and met us on the North Rim.
After 3-4 days in a cabin on the North Rim, I stepped off at ~5am. I stopped in Phantom ranch ate a sandwich and used to payphone to call my folks at the North Rim. They didn't answer so I left a message with the checkout desk (I think they were still at breakfast).
I did make it out of the inner gorge before the sun hit, but I was still on an exposed set of switchbacks below Indian Gardens that was getting absolutely brutal and I went through roughly two liters of water on that portion of the trail.
Once I made Indian Gardens I took my boots off, let my feet dry out a bit, changed my socks, ate another sandwich, and dumped all but one liter of water. From there to the rim there is water every 1.5 miles via the Bright Angel trail.
I beat my folks to the rim and when I met up with them was already licking an ice cream cone.
As a complete bit of random coincidence I ran into a geology classmate at the river. He was on a raft trip that had just pulled onto the beach.
You don't need a guide to do it, just train and know that you can make a 20+ mile hike. South to North is 6000ft down and 7000ft back up. You MUST be out of the inner gorge before the sun begins to beat down on the back Vishnu Schist. Folks use the typical forecast high for Phoenix as a corollary for the Inner Gorge, but be advised the black Vishnu Schist will soak up that sun and can feel absolutely brutal. There is a several mile long section of trail on the North Kaibab that stays deep in the inner gorge known as "The Box" long after you've left Phantom Ranch. So you do not want to be in The Box once the sun is beating down on it.