The Kwikee Lube is excellent, so I would continue to use that on the steps or anywhere else that needs lubrication with a film that doesn't attract dirt.
Your slideouts don't really need maintenance except to keep the mechanism clean. If you want to spray a dry film lube on the rack and pinion mechanism you may do so, but it isn't needed. If a hydraulic slide, don't apply lube to the rams, but you can wipe with ATF if you want to clean them.
A silicone preservative on the rubber parts doesn't hurt either, but again not really needed. The main thing is to inspect for loose rubber flaps and seals and re-attach any that are loose.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL