We have a 2021 Highland Ridge - Open Range stick and tin (conventional) trailer. It has a 3/8” walkable roof deck, although ours did not come with a ladder. I noticed the other day from my stepladde...
Interesting. Maybe you could visit the dealer and have a look (pictures) of similar units/roofs, someone on the forum with the same unit roof could check. If other units are smooth, it might be time to talk to the dealer service dept or check with the manufacturer.