Hands down, the best product to use is Rustoleum Rust Reformer. It comes in a spray can and doesn't simply cover up the rust. It actually reforms the rust into an inert material that does not rust again. Because it transforms the rust, obviously there needs to be rust there to transform. Because of this, you definitely don't want to remove all the rust before using. You can topcoat Rust Reformer with any color of paint (I use Reutoleum paint as my topcoat) you wish and the rust will not return. I have used this product for years and my wife says I should buy it by the case. When you own an acreage, you have lots of machines/tools that like to rust. THIS STUFF WORKS, I PROMISE!!!
Days camping (2016)----181 days
Days camping (2017) --- 82 days
2016 Wildcat MAXX 28RKX (33' TT), 2007 13' Scamp
2015 Ram Laramie Hemi, w/air suspension
30 years RV'ing
11 different RV's