OK, letīs list the known widebody human uses of cargo hold.
Classical DC-10-10 and Tristar 1 had standard lower hold galleys. Upper galleys and cargo holds through whole underbelly were options but the standard option was underbelly galleys.
Boeing 747 offered hold galley option, too - not sure how popular it was.
Pacific Southwest had their Tristars fitted with a passenger lounge in forward hold - and integral airstairs from that hold. Lockheed actually offered a hold fitted with seats occupiable on takeoff and landing, together with emergency exits, but I think not windows.
There are Boeing 747-s that are flying with 2 integral airstairs, ahead and behind the wing, complete with lobbies and stairs to main deck. VC-25 has integral stairs, in front for use of principals, in the rear for use of press.
Il-86 also has 2 integral airstairs in standard equipment - the hold contains cloakrooms for the winter clothes of the passengers.
So... it is practical and it is done. Can someone comment on the limitations?