There is a photo of the top of the Graf Zeppelin, sister ship of the Hindenburg, being repaired mid-flight[1], so the roof was accessible from inside (through the scaffolding of the interior gas bag area, rather than neatly for passengers), provided quite a large platform, and claimed to be stable in-flight. The gondola had promenade / viewing areas with "large windows which could be opened in flight" visible in the photos in [2], to address concerns about air pressure or temperature.

I don't know if they ever did put deckchairs on top but had they thought of it and wanted to do it, it might have worked out ok. (View was likely better inside, looking down).

[1] https://www.mutualart.com/Artwork/Repairing-the-hull-of-the-... - one of the people is sitting on the side of the photo. They were large enough, stable enough in-flight, and the top was accessible.

[2] https://www.airships.net/hindenburg/interiors/

Haha, it's a reference to the 2006 White House press correspondents dinner that Colbert hosted, and absolutely destroyed Bush at. It's on YouTube, and it's a great watch.