Ok, here's an important something that just occured to me.
When you installed the RP mod, did you check the 'Extra Content' box in the installer? That includes a few more features (and probably were separate mods before RP was released) including the armours. If you didn't tick the extra content you wont get the armour in-game.
If that's the case you might have to uninstall the mod, then reinstall it with the appropriate content
I'm not sure if the inclusion of the extras will corrupt your saves, neither do I know if the same will happen if you uninstall and reinstall the RP, so you might have to start another playthrough if you want the armours. But at the same time there are other extras aswell so the new playthrough will still have a few more surprises for you
But maybe your saves will be fine, I honestly don't know, so just prepare to restart if that turns out to be the case