I think you'll have to have a good weld shop access the frame ends to see if it can be done. I'd be hesitant to add that much weight so far back from the rear axles of the trailer. The 'bounce' and sudden up and down movement will put far more than 500 lbs. force on the receiver. You might look to adding 2 receivers, one at each frame rail end to double the support and reduce twisting on one hitch receiver.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI