I had a TT with no slide. It served the purpose at the time but we quickly realized we wanted to head for warm weather each year we knew we absolutely had to have a slide model. I always say sure buy a non slide but get steel toes shoes for when you are stepping on each others toes. Maybe for one person it would be fine.
Go look at both models, sit in them and have the other person move around, pretend that you are living in it. There are couples who live in 16 foot rigs or even vans but.......
In this first example picture getting up from the dinette while someone is at the sink, or sitting on the couch and someone wanting to pass. BUT, it does have a basement and bunk area that could store stuff.
Steel toesThis example has enough room for that second person to be in a recliner. I'm not recommending either of these manufacturers or models, they are just random examples that I found. They are not mine. I have a 30 fifth wheel with 14' slide.
Kicked backThe bed, sofa and dinette are pretty much standard. As I read your post again I see you have a service dog. I dont know anything about that and I could be wrong but my assumption is that a service dog will not be like my toy fox terrier but something larger and more dominant and robust like a shepherd etc. Again, you will now have a third "person" who wants to move around now and then or at minimum has to have a spot of it's own like a dog bed off to a corner or something.
You didnt mention what your tow vehicle is. You need to start there. If you dont have a TV you can go buy any TT or 5er you like and then buy the TV but you may be surprised what you have to buy. It could be a used half ton for $8,000 or a new diesel 4 door 4x4 for $55,000.
Unless you shop in the top end you will not find well insulated rv's. It's probably more likely that you would find it in high end 5er's. Not a rule, just in general.
So Georgia wont be a terrible state to heat in but I think it would be a tougher state to cool in. A model with one ac unit may not work. Now when you get into 2 ac units we're talking 50 amp service etc.
So post more about your TV or what your budget is. It's not being nosy, it will give a base point to build from and there are people on here who have done this stuff for 50 years so you can get excellent guidance. Be patient and put a plan together or you will be wasting money by buying and selling again to get the right one