On our previous Travel Trailer we replaced the dinette and pullout sofa with one long couch we put together from Ikea so we could all sit together. On our current Fifth Wheel, we removed the dinette and replaced it with a table that had the ability to fold out for the additional surface area.
Removing the stock furniture is pretty easy, just take your time and look for all the sneaky places they put screws. Sometimes it's hard to tell if it's a screw or staples holding it in place. My only concern would be weight. If it's going to be a huge increase in weight, it could put extra stress on the slide coming in and out. The slides are designed for a variety of use cases though, so assuming you aren't increasing the weight by hundreds of pounds, you should be ok.
Make sure you remember to measure to make sure it's going to fit through the door!
