A DRW would be much better in this case...
When you went to the scale, did you get the individual axle weights?
That would tell you how much weight is left on the rear axle (difference to RAWR).
With an SRW, you are probably pretty close to the max rating of the rear tires as is. Going too far over that number is not adviseable, you don't want one to blow while going down the highway with a TC in the back and a trailer in tow while over max load.
A hitch extension acts as a lever for the tongue weight of the trailer.
Better rent a U-Haul truck? Hire a moving company? Will make life a lot easier... maybe get some quotes before you decide.
