If it was mine I would put some labor into it and stop the problem. First remove the lines and put plugs in the cylinders so you can remove them. Then I would sand blast the rusted parts to strip any flaking metal and rust. If you have a local bridge painting company they use some of the best primers you will ever see for steel. Because of the salt and rain bridges see they use primers with far more zinc than normal primers. I've used a primer from a company called Wasser that was something like over 80% zinc when dry. Then get the correct color paint from Kubota. Chances are you'll never have an issue with it again.
The other option would be to replace the cylinder when they start to leak, and they will at the worst time, or try to have a welder replace the bungs. Chances are what's going to happen is the bung will get too thin and break when the cylinder is under load. For a loader that would mean with a bucket full of dirt that comes crashing down spraying hot oil everywhere.