My max weight with a 2000 7.3 SRW was about 13,200 pounds. I had put 19.5 tires and wheels on it, a Firestone airbag system that I ran light, you have heavier overhang so would need to up that. It seemed to work, there is quite a few people that say their rigs perform just fine. Your camper is about 600 pounds heavier than mine was.
Lot's of stuff seemed to break earlier than I expected.. it's not young.. 17 years old now. but I think I paid a price over and above what I should have if I obeyed the limitations as it said I should.
You are really over the limit for your rig.. really well over the limit. The only consideration, which I gently realized, is getting the whole thing to stop in a reasonable limit. Coming downhill in first gear on a switchback highway hoping I could make the next turn did not feel very good.
YMMV