lexusrx2: Sorry I didn't reply sooner! Congrats on you new bedliner! If you keep a tonneau over it, you really don't need Nason or Xtra. You might consider putting some Just Once (
www.justonce.com) on it a couple of times a year to keep it looking really good. It's sort of like putting a protectorant on your dash or seats to make them look good.
Rail caps: KEEP THEM ON!
Nason is not recommeded for commercial vehicles because it could eventually rub down with heavy continuous use. Xtra is supposed to be more durable.