I sprayed seal protectant on my seals last weekend just to keep them soft. My manual says the 'rack and pinion' stuff can be left alone, but I put a very light coat of spray lube designed for that on them as well. I can find a link if anyone is interested, but it's just basic RV lubes you can find on amazon. I'd be a little careful about spraying the rack that your slide runs over, if they say it's not needed at all, a super light film is probably all you need... my OCD dictates that I need it even though I supposedly don't, just go easy.
2016 27BHS Elite
2012 F-150 EcoBoost / Max Tow