Sounds like you are on the right track.
I too wonder if your wife's exercises could be preformed on the floor instead of in bed. Coming from a 2012 Northern Lite to a 2016 AF 990 like you are considering...I think the NL had more head room than the AF. Feels that way at least.
My 990 loaded puts me right close to the max on my 2013 Ram Dualy crew long bed 4x4. I ended up wth Stable Loads and rear air bags.
If I wasn't set on having a built in gene this time I would have gone with the 811 but still would keep my dually.