There are two places you can at least inquire at in NJ that have a pretty good reputation. One is:
Gerber RV Truck & Bus ----->
website HERE
60 Burlews CT
Hackensack NJ 07601
(201) 880-7124
They carry both Blue Ox and Roadmaster.
Another that several others have recommended is:
Country Road Automotive ----->
website HERE
580 Ryerson Road
Lincoln Park, NJ 07035
(973) 696-6625
They are an authorized Roadmaster dealer but also have access to a variety of towing equipment brands.
eta: another place that is an authorized Roadmaster dealer and has a good reputation but is down near Philadelphia that I forgot to mention is:
Hecht Trailers -- 2 locations south of Trenton ----->
website HERE
2075 Route 9
Toms River, NJ 08755
1788 Route 38
Mount Holly, NJ 08060