Not many Sprinter PC owners on here, but I can tell you after owning 2 Sprinters, an '08 and a '13, not PC's, that you are pushing the limits there on the weight. Be sure you have supplemental braking not just because of some state laws, but because the Sprinter's brakes are just good enough as it is. Not much leeway there.
Plan on no longer than 40k miles transmission fluid/filter changes, and it wouldn't be a bad idea to investigate a supplemental transmission fluid cooler. Remember you've only got a 3yr/36k warranty on that transmission, and you're talking over $4k to repair/replace that unit. (unless you've bought an extended warranty)
The NAG-1 transmission you have is not known for being very "heavy duty" if you will. I would shift up & down manually if I towed something that heavy with my Sprinter.
If you tow a lot, expect frequent, 50k, maybe sooner, brake replacements, probably the rears believe it or not.
Expect about a 1-2 mpg reduction in fuel mileage towing on the flatlands.
Hope this helps....