Make sure that the RV is rated for a 5000 lb toad? Sometimes they put a 5000 lb hitch in, but only rate the RV for a 3500 lb toad. Also check the difference between the GCVW and GVWR, this better be more than 5000 lb.
Why do I ask? There are not many Class C's that are rated for a 5000 lb toad.
The equalizing hitch does not allow a higher tongue weight, it just redistributes what you have to the front wheels of the towing vehicle. A 5000 lb hitch will be rated for a 500 lb tongue weight, never exceed this.
I would try the trailer without the equalizing hitch first.
To change the tongue weight modify how the trailer is loaded. The easiest way on a open vehicle trailer is to change the relationship of the car on the trailer over the trailer axles. Sometimes it means backing the car onto the trailer to put the engine in the rear (most vehicles have more weight on front axles). Some trailers provide a way to move the axles so help trim the load (usually not easy and requires a lot of wrenching with the trailer unloaded).
To measure tongue weight use a tongue weight scale
(Camping World used to carry them), or make one with a 2x4 and a bathroom scale.