Have a quick free consult with a real estate attorney (who you'll then use afterwards). It sounds like your agent is inexperienced and her boss doesn't want to support a deal where they won't get their big cut. I would not trust their word in what you can or can't do, since this is a contract issue - and in NJ contracts are done by lawyers.
You may wish to consider PA, assuming that you don't work in Philly (4% city tax). PA has much lower income tax than NJ (3.03 vs what you pay now - likely 5.25 or 6.37) and lower property taxes also. When you add those up (not counting possibly expensive association fees), it may be worth your while to move a touch across that river and reap the savings!
Other questions you may want to answer before you go ahead is whether the assigned contract is financeable by a lender when it is time to buy and whether it is insurable by a title-company.
Realtors might have an issue with what and when they get paid. do they only get a rental commission now, and a sales commission years down the road, or do they get a sales commission now.
Essex County, NJ