Not unless you’re wanting to venture way out in desert. I drove my class C out a bit.

When we were there, this past April, no 4x4 was needed. Ground was hard packed.

89A looks a little bit curvy between Flagstaff and Sedona. Would it be better to take the longer route on I-17 and approach the Loy Butte area from the south?

I am familiar with Loy Butte Road (also known as Forest Road 525) north of Hwy 89A from a couple years ago. As long as the weather has been dry, and you drive reasonably slowly, you will not need a 4x4. The road is a periodically maintained gravel road. There are places where it is bare slick rock, and places where water washes over the road. It is often bumpy and washboard, but passable. If it is wet, the mud becomes very slippery and the washes can be impassible. We boondocked at GPS 34.868109, -111.903752 with a great view of the red rocks.

No but I can be rutted and very muddy if it's rained so watch for any big slick mud patches and pot holes for clearance. It was raining and very wet a year ago when we were there. Did not use our 4x4 and there were plenty of class C, 2wd trucks and vans about. Not sure if you can get info from USFS office in the area now but they were helpful with road condition info.

We had an F150 and a 19 foot trailer. It wasn’t raining at the time and the road was a little washboard, but good. If it has been raining, then you might have a little bit harder time with the red mud. It might be pretty cold in December.

No, 4x4 is not needed. Road sometimes is washboard but very passable. Beautiful views.