Bottom line, your hitch can handle a 5x8 NO PROBLEM, and the only TRUCK that technically can't handle 5000# is one with a M5OD 5 speed stick. Being that you have a 2005, it would be a 4.2 V-6 if it has a 5 speed stick.

I've towed an enclosed 5x8 extensively with my truck, which has a 3500# official limit. NO problems.