Passenger evacuation for one. Right now, you can open some doors on the side of the tube and add more doors if needs be. That's a lot more of a challenge here.
Also, distributing passengers to a wider area inside the body can lead to greater instances of motion sickness.
Passengers will generally prefer having windows, which is also a challenge for this type of aircraft.
Main gear should be far enough forward that most of the weight is on it, but far enough aft that the nose isn't unloaded in aft CG conditions. It might be right where it needs to be. You'd have to know the CG location. You also need to account for an empty airplane with minimal fuel or it could tip up onto the tail. Tip up.
A large lifting area should at least mean slower landings, but gear should be long enough or far enough aft to flare a bit. You want the mains to touch first so you don't bounce or damage the nose gear.
It's not so much that it can't be done, but there are challenges.