Member drfife had an Arrow hitch and made this doo-dad using a receiver tube and a coupler. Leave the stinger in the hitch and then attach this receiver tube with coupler attached.
Many dealers use a forklift with a ball on one of the forks or a dedicated tug to move stuff around the lot.
Depending on what the dealer is doing for you and how long they are going to have it, you may wind up making several trips to move the trailer around for them. Other option is to remove the 3P when you drop it off.
My solution to the problem is to do all my own servicing and never take it back to the dealer.....