I feel very strongly that lubricants and brake systems don't mix, except for a small amount of specialized grease used to lube the sliding mechanism of calipers as preventive maintenance. I place a higher priority on stopping than on keeping my brakes shiney.
The line may get a little blurry here since brakes can fail as a result of rust and corrosion, and some feel that justifies the use of lubricants on brakes to prevent rust and corrosion. I don't believe that the lube just burns off on trailer systems, it ends up soaking into the brake pads, permanently reducing the effectiveness of your brake system.
If you leave your cars sitting for a long time (or sometimes not so long a time) the disks will rust. Would you spray them with a lubricant to keep them shiney? Of course not.
Rinse them down well when you can, at the ramp is better. SaltAway may help, but it is also supposed to leave some sort of residue behind to minimize corrosion. I've used it many times, but don't routinely use it on my brakes.
Maybe I'm lucky, I had TieDown disks on my last trailer and never had a problem with them. Rinse often, annual maintenance, they were perfect.
I've got Kodiak Stainless disks & calipers now, and treat them just the same. I've actually had to do more maintenance on them since I've never been able to stop several of the rear seals on my current trailer from leaking. I keep having to take everything apart on those wheels to clean up the grease and replace the seals and pads. The pads do absorb the grease, and seem to fall apart when I've tried to use degreasers on them.
Hopefully I've got the seal problem solved, I posted about that a little while back. Only time, and miles, will tell.
Bill | 
