Passing out with cigarette while AGM are gassing because of being overcharged? When - under the fool moon over your solar panel? :) ... Or while on the "quiet" 70 DB generator that your your neighbors can hear with closed doors and windows? I personally would worry about passing out with burning cigarette, no matter if there are any batteries there or not. That is - if I smoked.
A sealed compartment in RV? This is not a boat. On the boat there are waterproof bulkheads between compartments, all lids have gaskets with the same waterproof requirement. Vented are only spaces that need to be.
Storage spaces like under the bedroom in TT are not sealed, there is air circulating to the outside and to the inside. Inverters next to the battery - a problem, yes, more a problem with FLA than with AGM. I don't think AGM need extra vents in un-sealed compartment like TT storage area, but nothing stops you from making the same things as people do with FLA in this case - vent it through the hose to the outside.
Anybody remembers those VW Westy vans, with FLA battery inside the cabin, under the passenger seat? Is this "vented", really?