The rear flares attach with 2 or 3 bolts and a poppy thing (that's the technical term for those who didn't know). You can get to them by removing the rear inside plastic. Just remove all the nuts and pull the flare straight out from the outside.
The front flares attach inside the fenders and are tougher to get at, but if you persist and don't mind removing the air intake from the fender it should take around an hour total for the fronts. Inside the fender the flare attaches at 3-4 points. Again, just unscrew the nuts and pull it straight out. The toughest nuts to get to are in the back of the front fenders.
Don't forget to remove all the exterior screws as well.
I did this awhile back to coat them with line-x, but will likely remove altogether and line-x the lower body if I keep the truck past this summer.
I wouldn't want the risk of getting rhino or line-x on the paint, even with tape, and I would think it would be harder to get them completely clean inside and out. Now if it was a beater edition.......
I took mine off to spray them originally, then several months later touched them up with another 2 coats while on the truck... you just can't get as good coverage without full access to them. And unless you tape like crazy to prevent overspray you can't get far enough away to get a nice texture. The last few coats work great at about 18 inches.
I have to side with Junk. I tree...10 seconds...no effort...the look on your friends faces...priceless. In theory with turn around time you could be done in under 5 minutes. Of course you still may need that bodyman.