We enquired about the leveling of the slide when on the road also. We were told that it's not imperative that the tt is completely or perfectly level, but it shouldn't be too far off either; find the least incline if possible if you are stopping for lunch or shopping).
But FYI- there was something mentioned that same day about the running refridgerator, where, you want it not far off level.... here's the thing,
I can't remember which one is the concern whether it's the side-side, or front-back (they had a disected refridgerator on display and explained why when running the fridge the tt had to be leveled in one certain direction, but I can't remember off hand)