I have a 2011 F-250 4x4 crew cab, diesel, short box with heavy duty and camper package and carry an Arctic Fox 865. It is the only thing AF makes without a slide. It is very similar to a Wolf Creek 840 in size. You might need to add stable loads or airbags. The Sterling rear axel on your truck is rated over 10,000lbs, the tires and springs are rated lower.
Yes, it works with zero problems and yes you can tow a small trailer. Yes you will be bumping up on max GVWR and you will be well under your combined weight. Thousands upon thousands of truck campers drive down the road safely without dual wheels or 19.5's.
Have them load it on the truck so you can see the size of the thing. Most people do not realize how tall and wide it will be once loaded. You will probably need to do a couple of mods to address sway and sag.
The best thing I did while looking was run into a guy with a truck camper and look at his truck, in person. The internet is full of horror and terror stories that they heard on the internet.