I was thinking on the Discord meme of B3 Arabel Sewers and an idea hit me for Adhocs; why not have a selection of easily adjustable areas for adhocs for places like deeper in the sewers and forests around Arabel/Yulash; same could even potentially be done for the underdark. If memory serves, that's the biggest difficulties in running an adhoc is custom building an area for it, no?
Such areas do already exist in the module, just not readily accessible to players