What 2008 Monaco coach do you have? DP...Gasser? Length? And how do you know your jeep weighs 3987 lbs? Did you weigh it or is this also from a brochure?
When you refer to "hitch weight", you are actually referring to the amount of weight that can be put "on" the hitch....not what can be towed which would be called "towing capacity". Typically, the towing capacity is the difference between the coach's GVWR and its GCVWR.
I had a 2008 35' Safari Simba DP (which is actually a Monaco) and it had a towing capacity of 10,000 lbs. Most all Gassers today have a 5000 lb towing capacity.
So, please do give us more specific info on your coach.
Ron