Some very contradictory advice in this thread. From YES to NEVER, and all sorts of conditions and caveats in between. Enough different opinions to confuse anyone. So I suppose one more opinion won't make a difference...
I've routinely used 4LOW on bone dry concrete pavement, in reverse and forward, for the last 40 years... with no ill effects. However, for the specific truck and situation described in the original post... 4LOW should not be used at all.
Here's why: The OP has a 2017 1500 GM truck. The transfer case switch is electronic, uses an encoder motor, and the hubs are automated with the electronic switching of the transfer case. There is no easy way to segregate the engagement of the hubs from the engagement of the transfer case, without hacking into how the truck was originally manufactured, which would void the warranty on this 2017 model to the extent of the modifications and the systems effected. It gets worse... but more on that later on in this response.
By comparison, all of my 4WD trucks where I've successfully used 4LOW had all manual locking front hubs, whose actuation was completely separate from the manual floor mounted mechanical shift engagement of my transfer cases. So when I've been in 4LOW, I've actually been in 2LOW, because I didn't get out to lock the front hubs. And since my hubs didn't lock automatically, the dry pavement could not exert any influence or binding on the front axle relative to the rear... a conflict that would be communicated through the driveline, were they connected wheel to wheel. So even though my front axle was turning with the rear, the front tires were free to roll however they liked.
The respondents to this post who said YES, it's OK to use 4LO when backing a trailer up a dry concrete driveway, more than likely also have a manual hub locking system, or have disengaged their auto locking hub system, in order to take advantage of the gear reduction capacity of the transfer case while still in 2WD. They are right. For them it is A-OK.
The respondents to this post who said NO, never use 4LO on dry pavement, more than likely have 4WD vehicles where it is not practically possible to separate hub engagement from transfer case engagement. They are right also, because in those kinds of vehicles, including the OP's, a lot of damage can be done to the drive line in very short order when using 4LO on dry pavement. For them, it is not ok.
Now, to address the respondents who came up with a recipe for something in between... backing with 2WD for the first 90 degree, then using 4LO for the straight portion, then shifting back to 2WD for the last 90... that is a dicey proposition, because the OP said two things about the situation: 1) Uphill, and 2) Steep.
To understand why these two things are a problem, one first must understand how a 2017 1500 GM truck is shifted into, and out of, 4 LO. The transmission has to be in NEUTRAL. And the vehicle has to be ROLLING (or able to roll at about 1 mph). Now, add 7,500 lb trailer, uphill, and steep. This is not a combination of physics that one wants to shift around with. Where it gets worse is... GM states that severe damage can be done to the transfer case and driveline if the operator doesn't WAIT for the flashing light to go out before shifting out of neutral into gear again.
Note that Park is not an option. It's all electronic, and the transfer case will not shift if the vehicle is in any other gear except Neutral. And note that it takes a good few seconds for that flashing light to go out before being able to shift into a gear again... and this holds true in both directions... and for shifting into and out of 4LOW.
I have a GM 2500 Suburban with one of these electronic shifting transfer case arrangements. The only mechanical trouble I've ever had in this GM was with the encoder motor... it had lost it's orientation... after one of the very few times I used the transfer case. All four tires were off road, on soft gravel, on a level plane. For whatever reason, the encoder motor over traveled, and could not find it's way back to zero. Fortunately, I was still under warranty, and a new encoder motor sensor fixed the problem... although I suspect that if it was possible to reclock the encoder motor sensor, that might have fixed it also, but it was GM's dime, and GM's choice as to how to spend it.
The point is, I would not want to be coasting in neutral on a steep uphill driveway with a trailer in tow, trying to balance the lesser of two evils between driveline grenading or the transmission overheating... when the encoder motor looses it's place because I had to stand on the brakes to keep the rig from rolling before the slow motorized shift finished engaging.
To summarize, every one posting is correct, even if contradictory. It really depends on the equipment. For those who have all manual hubs, or aftermarket hubs, or modified vehicle wiring to disconnect the auto engagement of the hubs... then 4LO on dry pavement is not an issue. And even better control can be exerted if the transfer case is also manually shifted. But with all automatic hubs and electronic shifting 4WD arrangements, using 4LO on dry pavement will likely cause damage, and the Owner's Manual cautions against it.
Finally, some 1500 GM trucks and SUV's are AWD, and the engagement of the front occurs at the transfer case, not at the wheel ends. So not even aftermarket hubs will help in those vehicles. So at the end of the day, it depends on the truck. In my Ford trucks, each with manual transfer case and manual hubs, I use 4LO all the time, without ever engaging the front hubs. The gear reduction saves the transmission, because reverse is geared too high.
