Blue plastic water lines -- OK to use PVC cement?

Unless you are re-piping the whole house/RV, there is no reason to invest in a clamp system. The SharkBite type fittings are too easy and too reliable to not use for DIY work in modern times. They can be reused and refitted if you screw up the cut (clean and square with a cheap plastic Pex cutter followed by a Pex de-burring tool) and are available in brass and plastic. I like the plastic in the RV as it is more forgiving than brass if it should ever get frozen.