I got 1,200 lbs to work with - can I get a shell?

Now, those are real numbers.
With short camper you can roughly estimate that 90% of its weight will go on rear axle.
Be generous with safety margin.
Just becouse axle has capacity to carry it, doesn't have to make it comfortable.
Than ask me how da heck I managed to add 2300 lb to my camper.