Check with some of the local trailer dealers.  I know the dealer I have purchased several trailers from over the years has always had a loaner trailer that he has loaned me if my old trailer sold and the new trailer had not arrived. I've never asked him to rent it to me. It's always been, here use this for a couple of weeks until your's get here.  But I would imagine if there is a loaner sitting around, Some dealers may offer them to rent.  Just check around. 

Good luck. I'm sure you will have a great pack trip.