Did you type your numbers right? You weigh 17,880 pounds against a 16,000 GVWR? You're almost 2000 pounds over your weight rating? What's your OCCC? Maybe you could post a picture of your yellow weight sticker?
Does it look similar to this one from a 30R advertised online? 1352 pounds? Less than 900 pounds left after you fill it with water?
That I'm sure is a typo on the website - they yellow sticker would be official. Great that you weighed the coach - even with the sticker it's VERY hard to add it all up.
Nice looking coach and assuming it's the V-8 you'll have no problem towing the Jeep. I pull mine with the V-10 - I know it's back there and I can't race up a hill but it's respectable and handles OK.