I pulled my flares off a junkyard truck and painted them up with 5-6 coats. but I don't see why you couldn't just tape off around them. Just make sure to cover you entire truck to shield it from the overspray.
Krylon has several disadvantages. It is softer than 2K and not at durable. Most cars and trucks these days are made with plastic panels. They were all sprayed with 2K at the factory, not Krylon! Krylon is no longer the best medium for plastic. Also Krylon doesn't make paints to match your truck colors. NAPA 2K does. Maybe Eastwood 2K does too. 2K Lays down real easy, doesn't run drip, or sag as much, sets up, nice, flat, smooth.