Long-term preservation of a moderately rusted exhaust

I wish you a good day! Today I am facing the topic of exhaust system of my dear Kleinkrads. I am about to get this long-term, as it is also the original plant. Unfortunately, the rust makes a dash of my calculation. The question for you is therefore: Has someone already had their experiences with it? Is there an all-miracle cure or do you have to pick out the best for your needs? For the context: I drive very often with my R great, even if you don’t necessarily should. So I find myself on wet, dirty, or stony terrain again. I hope you can offer me here the one or other option and I thank micb in advance for any answer! With best regards