Hour RA is rated at 6080 lbs, which equals the stock tires. Springs are good to 6400, axle as noted 10,000.
Reality, a tire upgrade, common is a 265-75-16, nets you 6800 or so lbs of tires. RA on my 88 and 96 K3500 were 2200-2400 empty. Around 3000 lbs to put on RA before overloading things.
A dually version has a 7500 RA. You could do as I did to the 96, install a 6/1 spring pack vs stock 5/1, make them about 1/16-1/8" thicker, you have 8500 lbs of springs.....
A few things and yes you could handle family and hitch wieght. I would swag going to be 2500-3000 lbs as noted. 20-25% of gross wieght.
Marty